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main.go.html
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="Generator" content="Kate, the KDE Advanced Text Editor" />
<title>main.go</title>
</head>
<body>
<pre style='color:#1f1c1b;background-color:#ffffff;'>
<b>package</b> main
<b>import</b> (<span style='color:#bf0303;'>"fmt"</span>; <span style='color:#bf0303;'>"strconv"</span>; <span style='color:#bf0303;'>"reflect"</span>;<span style='color:#bf0303;'>"time"</span>;<span style='color:#bf0303;'>"sync"</span>;<span style='color:#bf0303;'>"runtime"</span>)
<b>var</b> K2 <span style='color:#0057ae;'>int</span>=<span style='color:#b08000;'>42</span> <span style='color:#898887;'>//scope Global level start uppercase,exposed</span>
<b>var</b> k3 <span style='color:#0057ae;'>int</span>=<span style='color:#b08000;'>42</span> <span style='color:#898887;'>//scope package level start lowercase</span>
<b>func</b> part3_variables(){
fmt.Println(<span style='color:#bf0303;'>"part3"</span>)
<span style='color:#898887;'>//variables</span>
fmt.Println(<span style='color:#bf0303;'>"hello world"</span>)
fmt.Println(<span style='color:#bf0303;'>"42"</span>)
<b>var</b> i <span style='color:#0057ae;'>int</span>
i=<span style='color:#b08000;'>42</span>
<b>var</b> j <span style='color:#0057ae;'>int</span>=<span style='color:#b08000;'>42</span>
<b>var</b> p <span style='color:#0057ae;'>float32</span>=<span style='color:#b08000;'>42</span>
a :=<span style='color:#b08000;'>42</span> <span style='color:#898887;'>// scope block level</span>
k :=<span style='color:#b08000;'>42</span> <span style='color:#898887;'>// shadowing</span>
fmt.Printf(<span style='color:#bf0303;'>"%v,%T </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,k,k) <span style='color:#898887;'>// 42 , int</span>
l :=<span style='color:#b08000;'>42</span>.
fmt.Println(<span style='color:#bf0303;'>"%v,%T"</span>,l,l) <span style='color:#898887;'>// 42 , float64 </span>
<b>var</b> ( u=<span style='color:#b08000;'>1</span> ; v=<span style='color:#b08000;'>2</span> )
<b>var</b> outerVeryLongName <span style='color:#0057ae;'>int</span>=<span style='color:#b08000;'>1</span>
<b>var</b> innerShorter <span style='color:#0057ae;'>int</span>=<span style='color:#b08000;'>1</span>
<b>var</b> t <span style='color:#0057ae;'>int</span>=<span style='color:#b08000;'>1</span>
fmt.Println(i,j,a,u,v,p,t,outerVeryLongName,innerShorter)
}
<b>func</b> part4_primitives(){
fmt.Println(<span style='color:#bf0303;'>"part4"</span>)
<b>var</b> i <span style='color:#0057ae;'>int</span>=<span style='color:#b08000;'>1</span>
<b>var</b> m <span style='color:#0057ae;'>float32</span>=<span style='color:#0057ae;'>float32</span>(<span style='color:#b08000;'>42</span>)
<b>var</b> s <span style='color:#0057ae;'>string</span> =<span style='color:#0057ae;'>string</span>(<span style='color:#b08000;'>42</span>)
fmt.Println(s) <span style='color:#898887;'>// "*"</span>
s=strconv.Itoa(i)
n,err :=strconv.Atoi(s)
fmt.Println(i,m,s,err)
<b>var</b> b <span style='color:#0057ae;'>bool</span>=<span style='color:#006e28;'>true</span>
h:= <span style='color:#b08000;'>1</span>==<span style='color:#b08000;'>1</span> <span style='color:#898887;'>//true</span>
<b>var</b> id <span style='color:#0057ae;'>int</span> =<span style='color:#b08000;'>0</span> <span style='color:#898887;'>//os default</span>
<b>var</b> i8 <span style='color:#0057ae;'>int8</span> =<span style='color:#b08000;'>0</span>
<b>var</b> i16 <span style='color:#0057ae;'>int16</span> =<span style='color:#b08000;'>0</span>
<b>var</b> i32 <span style='color:#0057ae;'>int32</span> =<span style='color:#b08000;'>0</span>
<b>var</b> i64 <span style='color:#0057ae;'>int64</span> =<span style='color:#b08000;'>0</span>
fmt.Println(b,n,h,id,i8,i16,i32,i64)
<b>var</b> uid <span style='color:#0057ae;'>uint</span> =<span style='color:#b08000;'>0</span> <span style='color:#898887;'>//os default</span>
<b>var</b> ui8 <span style='color:#0057ae;'>uint8</span> =<span style='color:#b08000;'>0</span>
<b>var</b> ui8b <span style='color:#0057ae;'>byte</span> =<span style='color:#b08000;'>0</span> <span style='color:#898887;'>//uint8</span>
<b>var</b> ui16 <span style='color:#0057ae;'>uint16</span> =<span style='color:#b08000;'>0</span>
<b>var</b> ui32 <span style='color:#0057ae;'>uint32</span> =<span style='color:#b08000;'>0</span>
fmt.Println(uid,ui8,ui8b,ui16,ui32)
<b>var</b> f32 <span style='color:#0057ae;'>float32</span> =<span style='color:#b08000;'>0</span>
<b>var</b> f64 <span style='color:#0057ae;'>float64</span> =<span style='color:#b08000;'>0</span>
fmt.Println(f32,f64)
<b>var</b> c1 <span style='color:#0057ae;'>complex64</span>=<span style='color:#b08000;'>1</span>+<span style='color:#b08000;'>2</span>i <span style='color:#898887;'>//2 float64 </span>
<b>var</b> c2 <span style='color:#0057ae;'>complex128</span>=<span style='color:#644a9b;'>complex</span>(<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>)
fmt.Println(c1,<span style='color:#644a9b;'>real</span>(c1),<span style='color:#644a9b;'>imag</span>(c1),c2)
<b>var</b> st <span style='color:#0057ae;'>string</span> =<span style='color:#bf0303;'>"alaindevos"</span>
<b>var</b> bb <span style='color:#0057ae;'>byte</span>= st[<span style='color:#b08000;'>2</span>]
fmt.Println(st,bb,st+st)
<span style='color:#898887;'>// s5[2]=string(42) assignent is illegal</span>
<span style='color:#898887;'>// Conversion to bytes to manipulate strings</span>
<b>var</b> cb[] <span style='color:#0057ae;'>byte</span>=[]<span style='color:#0057ae;'>byte</span>(st)
fmt.Println(cb) <span style='color:#898887;'>// ascii utf8 values</span>
<b>var</b> r1 <span style='color:#0057ae;'>int32</span> =<span style='color:#924c9d;'>'a'</span> <span style='color:#898887;'>// utf32 value</span>
<b>var</b> r2 <span style='color:#0057ae;'>rune</span> =<span style='color:#924c9d;'>'a'</span> <span style='color:#898887;'>// utf32 value</span>
fmt.Println(r1,r2) <span style='color:#898887;'>// ascii utf8 values</span>
<span style='color:#898887;'>//operators</span>
<b>var</b> b1 <span style='color:#0057ae;'>int</span> =<span style='color:#b08000;'>3</span>
<b>var</b> b2 <span style='color:#0057ae;'>int8</span> =<span style='color:#b08000;'>3</span>
<b>var</b> b3 <span style='color:#0057ae;'>int</span> =b1+<span style='color:#0057ae;'>int</span>(b2)
fmt.Println(b1,b2,b3)
<span style='color:#898887;'>// & : bitwise and , |:bitwise or , ^:bitwise xor , <<: bitshifting</span>
}
<b>func</b> part5_constants(){
fmt.Println(<span style='color:#bf0303;'>"part5"</span>)
<span style='color:#898887;'>//constants</span>
<b>const</b> myConst <span style='color:#0057ae;'>int</span> = <span style='color:#b08000;'>42</span>
fmt.Println(myConst)
<span style='color:#898887;'>//enumarated constants ,iota: counter</span>
<b>const</b> ( a=<span style='color:#006e28;'>iota</span> ; b=<span style='color:#006e28;'>iota</span> ; c=<span style='color:#006e28;'>iota</span>)
fmt.Println(a,b,c)
}
<b>func</b> part6_arrays(){
fmt.Println(<span style='color:#bf0303;'>"part6"</span>)
<span style='color:#898887;'>//arrays</span>
<b>var</b> ar1 [<span style='color:#b08000;'>3</span>]<span style='color:#0057ae;'>int</span>= [<span style='color:#b08000;'>3</span>]<span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>}
<b>var</b> ar2 [<span style='color:#b08000;'>3</span>]<span style='color:#0057ae;'>int</span>= [...]<span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>}
<b>var</b> ar3 [<span style='color:#b08000;'>3</span>]<span style='color:#0057ae;'>int</span>
ar3[<span style='color:#b08000;'>0</span>]=<span style='color:#b08000;'>1</span>
fmt.Println(ar1,ar2,ar3,<span style='color:#644a9b;'>len</span>(ar3)) <span style='color:#898887;'>//ar3[1]=0,ar3[2]=0</span>
<b>var</b> idx [<span style='color:#b08000;'>2</span>][<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span>= [<span style='color:#b08000;'>2</span>][<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span> { [<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span> {<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>0</span>} , [<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span> {<span style='color:#b08000;'>0</span>,<span style='color:#b08000;'>1</span>}}
<b>var</b> idy [<span style='color:#b08000;'>2</span>][<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span>=[...][<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span> { [<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span> {<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>0</span>} , [<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span> {<span style='color:#b08000;'>0</span>,<span style='color:#b08000;'>1</span>}}
<b>var</b> idz [<span style='color:#b08000;'>2</span>][<span style='color:#b08000;'>2</span>] <span style='color:#0057ae;'>int</span>
idz[<span style='color:#b08000;'>0</span>]=[...]<span style='color:#0057ae;'>int</span> {<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>0</span>}
idz[<span style='color:#b08000;'>1</span>]=[...]<span style='color:#0057ae;'>int</span> {<span style='color:#b08000;'>0</span>,<span style='color:#b08000;'>1</span>}
<b>var</b> idu [<span style='color:#b08000;'>2</span>][<span style='color:#b08000;'>2</span>]<span style='color:#0057ae;'>int</span>
idu=idz <span style='color:#898887;'>// equal sign and functions calls copies arrays</span>
fmt.Println(idx,idy,idz,idu)
<span style='color:#898887;'>//pointers</span>
idt:=&idu
idu[<span style='color:#b08000;'>0</span>][<span style='color:#b08000;'>0</span>]=<span style='color:#b08000;'>9</span> <span style='color:#898887;'>//changes idu and idt</span>
fmt.Println(idu,idt)
<span style='color:#898887;'>//slice ,refence type</span>
s1:=[]<span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>}
s2:=s1
s1[<span style='color:#b08000;'>0</span>]=<span style='color:#b08000;'>9</span> <span style='color:#898887;'>// changes s1 and s2</span>
fmt.Println(s1,s2)
s3:=s1[<span style='color:#b08000;'>0</span>:<span style='color:#b08000;'>3</span>] <span style='color:#898887;'>//s1[0] ,s1[1], s1[2] [first number is inclusive , second number is exlusive]</span>
s4:=s1[<span style='color:#b08000;'>1</span>:<span style='color:#b08000;'>2</span>] <span style='color:#898887;'>//s1[1]</span>
fmt.Println(s3,s4)
<span style='color:#898887;'>//convert array to slice</span>
sl1:=ar1[<span style='color:#b08000;'>0</span>:<span style='color:#644a9b;'>len</span>(ar1)]
fmt.Printf(<span style='color:#bf0303;'>"%v, %T </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,ar1,ar1) <span style='color:#898887;'>//[3]int </span>
fmt.Printf(<span style='color:#bf0303;'>"%v, %T </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,sl1,sl1) <span style='color:#898887;'>//[]int</span>
sl2:=<span style='color:#644a9b;'>make</span>([]<span style='color:#0057ae;'>int</span>,<span style='color:#b08000;'>3</span>) <span style='color:#898887;'>// makes a slice of length 3</span>
sl3:=<span style='color:#644a9b;'>make</span>([]<span style='color:#0057ae;'>int</span>,<span style='color:#b08000;'>3</span>,<span style='color:#b08000;'>5</span>) <span style='color:#898887;'>// makes a slice of length 3 and capacity 5</span>
sl3=<span style='color:#644a9b;'>append</span>(sl3,<span style='color:#b08000;'>8</span>,<span style='color:#b08000;'>9</span>) <span style='color:#898887;'>// length 5</span>
sl3=<span style='color:#644a9b;'>append</span>(sl3,<span style='color:#b08000;'>8</span>,<span style='color:#b08000;'>9</span>) <span style='color:#898887;'>// length 7</span>
fmt.Println(sl2,sl3,<span style='color:#644a9b;'>len</span>(sl3),<span style='color:#644a9b;'>cap</span>(sl3)) <span style='color:#898887;'>// length 5 capacity 10(it doubles)</span>
sl4:=sl3[<span style='color:#b08000;'>1</span>:] <span style='color:#898887;'>//removes first element</span>
sl5:=sl3[:<span style='color:#644a9b;'>len</span>(sl4)] <span style='color:#898887;'>//removes last element </span>
fmt.Println(sl4,sl5)
<span style='color:#898887;'>//split element</span>
sl6:=[]<span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>,<span style='color:#b08000;'>4</span>,<span style='color:#b08000;'>5</span>,<span style='color:#b08000;'>6</span>,<span style='color:#b08000;'>7</span>,<span style='color:#b08000;'>8</span>,<span style='color:#b08000;'>9</span>}
fmt.Println(sl6)
sl7:=sl6[:<span style='color:#b08000;'>2</span>]
sl8:=sl6[<span style='color:#b08000;'>2</span>:]
fmt.Println(sl6,sl7,sl8)
}
<b>func</b> part7_maps(){
fmt.Println(<span style='color:#bf0303;'>"part7"</span>)
<span style='color:#898887;'>//maps collection type </span>
<span style='color:#898887;'>//maps have no fixed order</span>
<span style='color:#898887;'>//data is passed by reference</span>
statepopulation:=<b>map</b>[<span style='color:#0057ae;'>string</span>]<span style='color:#0057ae;'>int</span>{
<span style='color:#bf0303;'>"denderleeuw"</span>:<span style='color:#b08000;'>1500</span>,
<span style='color:#bf0303;'>"aalst"</span>:<span style='color:#b08000;'>3500</span>,
}
map2:=<span style='color:#644a9b;'>make</span>(<b>map</b>[<span style='color:#0057ae;'>string</span>]<span style='color:#0057ae;'>int</span>)
statepopulation[<span style='color:#bf0303;'>"ninove"</span>]=<span style='color:#b08000;'>300</span>
<span style='color:#644a9b;'>delete</span>(statepopulation,<span style='color:#bf0303;'>"denderleeuw"</span>)
fmt.Println(statepopulation,map2,<span style='color:#644a9b;'>len</span>(statepopulation))
pop,ok:=statepopulation[<span style='color:#bf0303;'>"denderleeuw"</span>]
fmt.Println(pop,ok)
<span style='color:#898887;'>//struct , datasets are copied</span>
<b>type</b> Doctor <b>struct</b>{
number <span style='color:#0057ae;'>int</span>
name <span style='color:#0057ae;'>string</span>
companions []<span style='color:#0057ae;'>string</span>
}
aDoctor:=Doctor{
number:<span style='color:#b08000;'>3</span>,
name:<span style='color:#bf0303;'>"Alain"</span>,
companions: []<span style='color:#0057ae;'>string</span>{<span style='color:#bf0303;'>"Eddy"</span>,<span style='color:#bf0303;'>"Emiel"</span>},
}
fmt.Println(aDoctor,aDoctor.companions[<span style='color:#b08000;'>1</span>])
<span style='color:#898887;'>//anonymous struct , for short lived models</span>
aDoctor2:=<b>struct</b>{
number <span style='color:#0057ae;'>int</span>
name <span style='color:#0057ae;'>string</span>
} {
number:<span style='color:#b08000;'>16</span>,
name:<span style='color:#bf0303;'>"john"</span>,
}
bDoctor:=aDoctor <span style='color:#898887;'>//copy</span>
cDoctor:=&aDoctor <span style='color:#898887;'>//pointer</span>
fmt.Println(aDoctor2,bDoctor,cDoctor)
<span style='color:#898887;'>//embedding , for base behaviour, not for polymorphism, or interchanging object types</span>
<b>type</b> Animal <b>struct</b>{
Name <span style='color:#0057ae;'>string</span>
}
<b>type</b> Bird <b>struct</b>{
Animal <span style='color:#898887;'>// inner,type "inheritence",embedding </span>
speed <span style='color:#0057ae;'>float32</span>
}
bi1:=Bird{}
bi1.Name=<span style='color:#bf0303;'>"emu"</span>
bi1.speed=<span style='color:#b08000;'>48</span>
bi2:=Bird{
Animal: Animal{Name :<span style='color:#bf0303;'>"emu"</span>},
speed: <span style='color:#b08000;'>48</span>,
}
fmt.Println(bi1,bi2)
<span style='color:#898887;'>//tags</span>
<b>type</b> Animal2 <b>struct</b>{
Name <span style='color:#0057ae;'>string</span> <span style='color:#bf0303;'>`required max:"100"`</span> <span style='color:#898887;'>//restrictions</span>
}
atype:=reflect.TypeOf(Animal2{})
afield,_:=atype.FieldByName(<span style='color:#bf0303;'>"Name"</span>)
atag:=afield.Tag
fmt.Println(atag) <span style='color:#898887;'>//prints : required max:"100"</span>
}
<b>func</b> part8_if() {
fmt.Println(<span style='color:#bf0303;'>"part8"</span>)
<span style='color:#898887;'>//Control Flow</span>
<span style='color:#898887;'>//if</span>
<b>if</b> <span style='color:#006e28;'>true</span> {
fmt.Println(<span style='color:#bf0303;'>"true"</span>)
}
<span style='color:#898887;'>//if else</span>
<b>if</b> ok:=(<span style='color:#b08000;'>1</span>==<span style='color:#b08000;'>1</span>)&&(<span style='color:#b08000;'>0</span>==<span style='color:#b08000;'>0</span>)&&(!<span style='color:#006e28;'>false</span>);ok {
fmt.Println(ok)
} <b>else</b> {
fmt.Println(<span style='color:#bf0303;'>"untrue"</span>)
}
<span style='color:#898887;'>//if else if </span>
mycount:=<span style='color:#b08000;'>3</span>.<span style='color:#b08000;'>5</span>
<b>if</b> mycount < <span style='color:#b08000;'>3</span>{
fmt.Println(<span style='color:#bf0303;'>"mycount<3"</span>)
} <b>else</b> <b>if</b> mycount < <span style='color:#b08000;'>4</span>{
fmt.Println(<span style='color:#bf0303;'>"3<=mycount<4"</span>)
} <b>else</b> {
fmt.Println(<span style='color:#bf0303;'>"4<=mycount"</span>)
}
<span style='color:#898887;'>//switch</span>
<b>switch</b> <span style='color:#b08000;'>3</span> {
<b>case</b> <span style='color:#b08000;'>2</span>:
fmt.Println(<span style='color:#bf0303;'>"2"</span>)
<b>case</b> <span style='color:#b08000;'>3</span>:
fmt.Println(<span style='color:#bf0303;'>"3"</span>)
<b>case</b> <span style='color:#b08000;'>4</span>:
fmt.Println(<span style='color:#bf0303;'>"4"</span>)
<b>default</b> :
fmt.Println(<span style='color:#bf0303;'>"else"</span>)
}
<span style='color:#898887;'>//switch</span>
<b>switch</b> i:=<span style='color:#b08000;'>1</span>+<span style='color:#b08000;'>1</span>;i+<span style='color:#b08000;'>1</span> {
<b>case</b> <span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>3</span>,<span style='color:#b08000;'>5</span>:
fmt.Println(<span style='color:#bf0303;'>"odd"</span>)
<b>case</b> <span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>4</span>,<span style='color:#b08000;'>6</span>:
fmt.Println(<span style='color:#bf0303;'>"even"</span>)
<b>default</b> :
fmt.Println(<span style='color:#bf0303;'>"unknown"</span>)
}
<span style='color:#898887;'>//switch with implicit break between cases</span>
ii:=<span style='color:#b08000;'>3</span>.<span style='color:#b08000;'>5</span>
<b>switch</b> {
<b>case</b> ii<<span style='color:#b08000;'>3</span>:
fmt.Println(<span style='color:#bf0303;'>"ii<3"</span>)
<b>case</b> (<span style='color:#b08000;'>3</span><=ii) && (ii<=<span style='color:#b08000;'>4</span>):
fmt.Println(<span style='color:#bf0303;'>"3<=ii<=4"</span>)
<b>case</b> ii><span style='color:#b08000;'>4</span>:
fmt.Println(<span style='color:#bf0303;'>"ii>4"</span>)
<b>default</b>:
}
<span style='color:#898887;'>//fallthrough</span>
<b>switch</b> {
<b>case</b> ii<<span style='color:#b08000;'>3</span>:
fmt.Println(<span style='color:#bf0303;'>"ii<3"</span>)
<b>fallthrough</b>
<b>case</b> ii<<span style='color:#b08000;'>4</span>:
fmt.Println(<span style='color:#bf0303;'>"ii<4"</span>)
<b>fallthrough</b>
<b>case</b> ii<<span style='color:#b08000;'>5</span>:
fmt.Println(<span style='color:#bf0303;'>"ii<5"</span>)
<b>fallthrough</b>
<b>default</b>:
}
<span style='color:#898887;'>//An interface can be any type , here int </span>
<span style='color:#898887;'>//switch of type</span>
<b>var</b> ty <b>interface</b>{} = <span style='color:#b08000;'>1</span>
<b>switch</b> ty.(<b>type</b>) {
<b>case</b> <span style='color:#0057ae;'>int</span>:
fmt.Println(<span style='color:#bf0303;'>"ty has type int"</span>)
<b>case</b> <span style='color:#0057ae;'>float64</span>:
fmt.Println(<span style='color:#bf0303;'>"ty has type float64"</span>)
<b>break</b>
fmt.Println(<span style='color:#bf0303;'>"do not execute this"</span>)
<b>default</b>:
}
}
<b>func</b> part9_looping() {
fmt.Println(<span style='color:#bf0303;'>"part9"</span>)
<span style='color:#898887;'>//For looping</span>
<b>for</b> a:=<span style='color:#b08000;'>1</span>;a<=<span style='color:#b08000;'>3</span>;a++ {
fmt.Println(a)
}
a:=<span style='color:#b08000;'>1</span>
<b>for</b> ;a<=<span style='color:#b08000;'>3</span>;a++ {
fmt.Println(a)
}
a=<span style='color:#b08000;'>1</span>
<span style='color:#898887;'>//while </span>
<b>for</b> ;a<=<span style='color:#b08000;'>3</span>;{
fmt.Println(a)
a++
}
<span style='color:#898887;'>//while with sugar</span>
a=<span style='color:#b08000;'>1</span>
<b>for</b> a<=<span style='color:#b08000;'>3</span>{
fmt.Println(a)
a++
}
<span style='color:#898887;'>// do while</span>
a=<span style='color:#b08000;'>1</span>
<b>for</b> {
fmt.Println(a)
a++
<b>if</b> a==<span style='color:#b08000;'>4</span> {
<b>break</b>
}
}
<span style='color:#898887;'>// continue</span>
a=<span style='color:#b08000;'>1</span>
<b>for</b>{
fmt.Println(a)
a++
<b>if</b> a<<span style='color:#b08000;'>4</span>{
<b>continue</b>
}
<b>break</b>
}
<span style='color:#898887;'>//Label to break out of nested loops</span>
Myouter:
<b>for</b> i1:=<span style='color:#b08000;'>0</span>;i1<<span style='color:#b08000;'>3</span>;i1++ {
<b>for</b> i2:=<span style='color:#b08000;'>0</span>;i2<<span style='color:#b08000;'>3</span>;i2++ {
i3:=i1*i2;
fmt.Println(i3)
<b>if</b> (i3><span style='color:#b08000;'>5</span>) {
<b>break</b> Myouter
}
}
}
<span style='color:#898887;'>//Collection for loops</span>
<span style='color:#898887;'>//slice </span>
sl:= []<span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>3</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>1</span>}
<b>for</b> k,v:=<b>range</b> sl {
<span style='color:#898887;'>//k is key or index ; v is the value</span>
fmt.Println(k,v)
}
<span style='color:#898887;'>//array </span>
<span style='color:#898887;'>//slice </span>
ar:= [<span style='color:#b08000;'>3</span>]<span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>3</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>1</span>}
<b>for</b> k,v:=<b>range</b> ar {
<span style='color:#898887;'>//k is key or index ; v is the value</span>
fmt.Println(k,v)
}
<span style='color:#898887;'>//map</span>
mapa:=<b>map</b>[<span style='color:#0057ae;'>int</span>]<span style='color:#0057ae;'>int</span> {
<span style='color:#b08000;'>0</span>: <span style='color:#b08000;'>3</span>,
<span style='color:#b08000;'>1</span>: <span style='color:#b08000;'>2</span>,
<span style='color:#b08000;'>2</span>: <span style='color:#b08000;'>1</span>,
}
<b>for</b> k,v:=<b>range</b> mapa {
<span style='color:#898887;'>//k is key or index ; v is the value</span>
fmt.Println(k,v)
}
s:=<span style='color:#bf0303;'>"321"</span>
<b>for</b> k,v:=<b>range</b> s {
<span style='color:#898887;'>//k is key or index ; v is the value</span>
fmt.Println(k,<span style='color:#0057ae;'>string</span>(v))
}
<span style='color:#898887;'>// _ : dummy or placeholder</span>
s=<span style='color:#bf0303;'>"321"</span>
<b>for</b> _,v:=<b>range</b> s {
<span style='color:#898887;'>//k is key or index ; v is the value</span>
fmt.Println(<span style='color:#0057ae;'>string</span>(v))
}
}
<b>func</b> part10_defer() {
fmt.Println(<span style='color:#bf0303;'>"part10"</span>)
<span style='color:#898887;'>//defer , order is lifo , used to close resources</span>
<span style='color:#898887;'>// E.g. file.open</span>
<span style='color:#898887;'>// defer file.close</span>
{
fmt.Println(<span style='color:#bf0303;'>"a"</span>)
<b>defer</b> fmt.Println(<span style='color:#bf0303;'>"1"</span>)
fmt.Println(<span style='color:#bf0303;'>"b"</span>)
}
{
<b>defer</b> fmt.Println(<span style='color:#bf0303;'>"2"</span>)
fmt.Println(<span style='color:#bf0303;'>"a"</span>)
<b>defer</b> fmt.Println(<span style='color:#bf0303;'>"3"</span>)
fmt.Println(<span style='color:#bf0303;'>"b"</span>)
}
<span style='color:#898887;'>//Prints "start"</span>
{
fmt.Println(<span style='color:#bf0303;'>"A:-------------"</span>)
a:=<span style='color:#bf0303;'>"4:start"</span>
<b>defer</b> fmt.Println(a)
a=<span style='color:#bf0303;'>"4:end"</span>
}
<span style='color:#898887;'>//Panics (exceptions) ,used when an error returned must be handled.</span>
<span style='color:#898887;'>//Note: Panics happen after defer statements are executed.</span>
<span style='color:#898887;'>//Panics don't have to be fatal</span>
{
fmt.Println(<span style='color:#bf0303;'>"B:------------"</span>)
fmt.Println(<span style='color:#bf0303;'>"Take resource"</span>)
<b>defer</b> fmt.Println(<span style='color:#bf0303;'>"5:Release resource"</span>)
a,b:=<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>0</span>.<span style='color:#b08000;'>1</span>
<b>if</b> (b==<span style='color:#b08000;'>0</span>){
<span style='color:#644a9b;'>panic</span>(<span style='color:#bf0303;'>"runtime error: integer divide by zero Byebye"</span>)
}
fmt.Println(a,b)
<span style='color:#898887;'>// ans:=a/b </span>
<span style='color:#898887;'>// fmt.Println(ans)</span>
}
fmt.Println(<span style='color:#bf0303;'>"--------------"</span>)
fmt.Println(<span style='color:#bf0303;'>"Deferred stuff"</span>)
}
<b>func</b> part11_pointers() {
fmt.Println(<span style='color:#bf0303;'>"part11"</span>)
<span style='color:#898887;'>//Pointers</span>
<b>var</b> a <span style='color:#0057ae;'>int</span> = <span style='color:#b08000;'>42</span>
<b>var</b> pa *<span style='color:#0057ae;'>int</span> = &a <span style='color:#898887;'>//address</span>
fmt.Println(pa) <span style='color:#898887;'>//address </span>
fmt.Println(*pa) <span style='color:#898887;'>//dereference operator, value </span>
*pa=<span style='color:#b08000;'>7</span>
fmt.Println(*pa) <span style='color:#898887;'>//dereference operator, value </span>
<b>var</b> ar=[<span style='color:#b08000;'>3</span>]<span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>}
p0:=&ar[<span style='color:#b08000;'>0</span>]
p1:=&ar[<span style='color:#b08000;'>1</span>]
<span style='color:#898887;'>// p2:=&ar[1]+8 //invalid</span>
fmt.Printf(<span style='color:#bf0303;'>"%v %p %p </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,ar,p0,p1)
<b>type</b> aStruct <b>struct</b>{
aint <span style='color:#0057ae;'>int</span>
}
<b>var</b> ps *aStruct
ps=&aStruct{ aint: <span style='color:#b08000;'>42</span>}
fmt.Println(ps)
<b>var</b> ps2 *aStruct
fmt.Println(ps2) <span style='color:#898887;'>// <nil></span>
ps2=<span style='color:#644a9b;'>new</span>(aStruct)
fmt.Println(ps2) <span style='color:#898887;'>// &{0}</span>
(*ps2).aint=<span style='color:#b08000;'>5</span>
fmt.Println(ps2) <span style='color:#898887;'>// &{5}</span>
fmt.Println((*ps2).aint) <span style='color:#898887;'>// 5</span>
fmt.Println(ps2.aint) <span style='color:#898887;'>// sugar</span>
<span style='color:#898887;'>//array ,copies</span>
ar=[<span style='color:#b08000;'>3</span>] <span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>}
ar2:=ar <span style='color:#898887;'>//copies </span>
fmt.Println(ar,ar2)
ar[<span style='color:#b08000;'>1</span>]=<span style='color:#b08000;'>42</span>
fmt.Println(ar,ar2)
<span style='color:#898887;'>//slice , by reference </span>
<b>var</b> sl=[] <span style='color:#0057ae;'>int</span>{<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>}
sl2:=sl <span style='color:#898887;'>// </span>
fmt.Println(sl,sl2)
sl[<span style='color:#b08000;'>1</span>]=<span style='color:#b08000;'>42</span> <span style='color:#898887;'>//changes both</span>
fmt.Println(sl,sl2)
fmt.Printf(<span style='color:#bf0303;'>"%p %p </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,&sl,&sl2)
fmt.Printf(<span style='color:#bf0303;'>"%p %p </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,&sl[<span style='color:#b08000;'>1</span>],&sl2[<span style='color:#b08000;'>1</span>]) <span style='color:#898887;'>//same</span>
<span style='color:#898887;'>//map , by reference </span>
ma:=<b>map</b>[<span style='color:#0057ae;'>string</span>]<span style='color:#0057ae;'>string</span>{<span style='color:#bf0303;'>"aaa"</span>:<span style='color:#bf0303;'>"111"</span>,<span style='color:#bf0303;'>"bbb"</span>:<span style='color:#bf0303;'>"222"</span>}
ma2:=ma
fmt.Println(ma,ma2)
ma[<span style='color:#bf0303;'>"bbb"</span>]=<span style='color:#bf0303;'>"333"</span> <span style='color:#898887;'>//changes both</span>
fmt.Println(ma,ma2)
<span style='color:#898887;'>//Be carefull passing maps and slices in an application can change underlying data</span>
<span style='color:#898887;'>//This does not happen with primitives,arrays,structs [There normally everything is copied]</span>
}
<span style='color:#898887;'>//functions</span>
<b>func</b> myFunction1(msg <span style='color:#0057ae;'>string</span>,idx <span style='color:#0057ae;'>int</span>) {
fmt.Println(msg,idx)
}
<span style='color:#898887;'>//Same types</span>
<b>func</b> myFunction2(msg1,msg2 <span style='color:#0057ae;'>string</span>) {
fmt.Println(msg1,msg2)
}
<span style='color:#898887;'>//Pointers</span>
<b>func</b> myFunction3(msg *<span style='color:#0057ae;'>string</span>) {
fmt.Println(*msg)
*msg=<span style='color:#bf0303;'>"1234567"</span>
}
<b>func</b> mySum(msg <span style='color:#0057ae;'>string</span>,values ...<span style='color:#0057ae;'>int</span>){
fmt.Println(values)
fmt.Printf(<span style='color:#bf0303;'>"%T </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,values) <span style='color:#898887;'>//slice</span>
result:=<span style='color:#b08000;'>0</span>
<b>for</b> _,v:=<b>range</b> values{
result +=v
}
fmt.Println(msg,result)
}
<b>func</b> mySum2(values ...<span style='color:#0057ae;'>int</span>) <span style='color:#0057ae;'>int</span> {
result:=<span style='color:#b08000;'>0</span>
<b>for</b> _,v:=<b>range</b> values{
result +=v
}
<b>return</b> result
}
<b>func</b> mySum3(values ...<span style='color:#0057ae;'>int</span>) *<span style='color:#0057ae;'>int</span> {
result:=<span style='color:#b08000;'>0</span>
<b>for</b> _,v:=<b>range</b> values{
result +=v
}
<b>return</b> &result <span style='color:#898887;'>// the memory is moved from local stack to heap memory</span>
}
<span style='color:#898887;'>//named variables ,syntactical sugar</span>
<b>func</b> mySum4(values ...<span style='color:#0057ae;'>int</span>) (myresult <span style='color:#0057ae;'>int</span>) {
myresult=<span style='color:#b08000;'>0</span>
<b>for</b> _,v:=<b>range</b> values{
myresult +=v
}
<b>return</b>
}
<span style='color:#898887;'>//multiple return values and error type</span>
<b>func</b> divide(t,n <span style='color:#0057ae;'>int</span>)(<span style='color:#0057ae;'>int</span>,<span style='color:#0057ae;'>error</span>) {
<span style='color:#898887;'>//error checking at beginning</span>
<b>if</b> n==<span style='color:#b08000;'>0</span> {
<b>return</b> <span style='color:#b08000;'>0</span>,fmt.Errorf(<span style='color:#bf0303;'>"Cannot divide by zero"</span>)
} <b>else</b> {
<b>return</b> (t/n),<span style='color:#006e28;'>nil</span>
}
}
<b>func</b> part12_alpha() {
fmt.Println(<span style='color:#bf0303;'>"part12_alpha"</span>)
<span style='color:#898887;'>//two parameters</span>
myFunction1(<span style='color:#bf0303;'>"Hallo"</span>,<span style='color:#b08000;'>2</span>)
<span style='color:#898887;'>//same types</span>
myFunction2(<span style='color:#bf0303;'>"Hallo"</span>,<span style='color:#bf0303;'>"Daar"</span>)
<span style='color:#898887;'>//Pass by reference ,is faster</span>
astring:=<span style='color:#bf0303;'>"Alain"</span>
myFunction3(&astring)
fmt.Println(astring) <span style='color:#898887;'>//1234567</span>
<span style='color:#898887;'>//variable arguments</span>
mySum(<span style='color:#bf0303;'>"The sum is :"</span>,<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>)
s:=mySum2(<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>)
fmt.Println(s)
<b>var</b> s2 *<span style='color:#0057ae;'>int</span>=mySum3(<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>)
fmt.Println(<span style='color:#bf0303;'>"The sum is"</span>,*s2)
fmt.Println(mySum4(<span style='color:#b08000;'>1</span>,<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>))
<b>var</b> d <span style='color:#0057ae;'>int</span>
<b>var</b> err <span style='color:#0057ae;'>error</span>
d,err=divide(<span style='color:#b08000;'>10</span>,<span style='color:#b08000;'>0</span>)
fmt.Println(d,err)
<b>if</b>(err!=<span style='color:#006e28;'>nil</span>){
fmt.Println(err)
} <b>else</b> {
fmt.Println(d)
}
<span style='color:#898887;'>//declare an anonymous function i.e. without a name</span>
<b>func</b> () {
msg:=<span style='color:#bf0303;'>"Hallo"</span> <span style='color:#898887;'>//isolated scope</span>
fmt.Println(msg)
} () <span style='color:#898887;'>//invoke immediately</span>
<span style='color:#898887;'>//with loop </span>
<b>for</b> i:=<span style='color:#b08000;'>0</span>;i<<span style='color:#b08000;'>3</span>;i++ {
<b>func</b> (j <span style='color:#0057ae;'>int</span>) {
fmt.Println(j)
} (i) <span style='color:#898887;'>//invoke immediately</span>
}
<span style='color:#898887;'>//anonymous function as variable</span>
k:=<b>func</b>(){
fmt.Println(<span style='color:#bf0303;'>"hi"</span>)
}
k() <span style='color:#898887;'>//invoke</span>
<b>var</b> maal <b>func</b>(<span style='color:#0057ae;'>int</span>,<span style='color:#0057ae;'>int</span>) (<span style='color:#0057ae;'>int</span>)
maal=<b>func</b>(a <span style='color:#0057ae;'>int</span>,b <span style='color:#0057ae;'>int</span>)(c <span style='color:#0057ae;'>int</span>){
c=a*b
<b>return</b>
}
fmt.Println(maal(<span style='color:#b08000;'>2</span>,<span style='color:#b08000;'>3</span>))
}
<span style='color:#898887;'>//methods</span>
<b>type</b> greeter <b>struct</b> {
greeting <span style='color:#0057ae;'>string</span>
name <span style='color:#0057ae;'>string</span>
}
<span style='color:#898887;'>//methods , functions acting on context (any type,eg structs)</span>
<span style='color:#898887;'>//here the struct greeter is copied and we can access the fields</span>
<span style='color:#898887;'>//we cannot access the struct itself</span>
<b>func</b> (g greeter) greet(){
fmt.Println(g.greeting,g.name)
g.name=<span style='color:#bf0303;'>"Eddy"</span> <span style='color:#898887;'>//no effect</span>
}
<span style='color:#898887;'>//pointer receiver</span>
<b>func</b> (g *greeter) greet2(){
fmt.Println(g.greeting,g.name)
g.name=<span style='color:#bf0303;'>"Emiel"</span> <span style='color:#898887;'>//with effect</span>
}
<b>func</b> part12_beta(){
fmt.Println(<span style='color:#bf0303;'>"part12_beta"</span>)
h:=greeter {
greeting: <span style='color:#bf0303;'>"Hello"</span>,
name:<span style='color:#bf0303;'>"Alain"</span>,
}
<span style='color:#898887;'>//methods , functions acting on an value,here greeter </span>
h.greet() <span style='color:#898887;'>//Alain</span>
h.greet() <span style='color:#898887;'>//Alain</span>
h.greet2() <span style='color:#898887;'>//Alain</span>
h.greet2() <span style='color:#898887;'>//Emiel</span>
}
<b>func</b> part12_functions() {
part12_alpha()
part12_beta()
}
<span style='color:#898887;'>//definition , it takes a slice of bytes and write to something returning bytes written</span>
<span style='color:#898887;'>//naming convention is method name, here Write + er = Writer</span>
<b>type</b> Writer <b>interface</b> {
Write([]<span style='color:#0057ae;'>byte</span>) (<span style='color:#0057ae;'>int</span>,<span style='color:#0057ae;'>error</span>)
}
<span style='color:#898887;'>//implicit implement , a struct </span>
<b>type</b> ConsoleWriter <b>struct</b> {}
<span style='color:#898887;'>//Print to console </span>
<b>func</b> (cw ConsoleWriter) Write(data []<span style='color:#0057ae;'>byte</span>)(<span style='color:#0057ae;'>int</span>,<span style='color:#0057ae;'>error</span>){
n,err := fmt.Println(<span style='color:#0057ae;'>string</span>(data))
<b>return</b> n,err
}
<b>func</b> part13_writer() {
fmt.Println(<span style='color:#bf0303;'>"part13_writer"</span>)
<span style='color:#898887;'>// interfaces store behaviours, method definitions</span>
<span style='color:#898887;'>// w is something that implements the writer interface </span>
<b>var</b> w Writer=ConsoleWriter{}
<span style='color:#898887;'>// Polymorphic behaviour, w could be TcpWriter ...</span>
w.Write([]<span style='color:#0057ae;'>byte</span>(<span style='color:#bf0303;'>"Interface "</span>))
}
<b>type</b> Incrementer <b>interface</b> {
Increment() <span style='color:#0057ae;'>int</span>
}
<span style='color:#898887;'>//type alias</span>
<b>type</b> IntCounter <span style='color:#0057ae;'>int</span>
<span style='color:#898887;'>//implementation for the interface </span>
<b>func</b> (ic *IntCounter) Increment() <span style='color:#0057ae;'>int</span> {
(*ic)=(*ic)+<span style='color:#b08000;'>1</span>
<b>return</b> <span style='color:#0057ae;'>int</span>(*ic)
}
<b>func</b> part13_incrementer(){
fmt.Println(<span style='color:#bf0303;'>"part13_incrementer"</span>)
myInt:=IntCounter(<span style='color:#b08000;'>0</span>)
<b>var</b> inc Incrementer=&myInt
<b>for</b> i:=<span style='color:#b08000;'>0</span>;i<<span style='color:#b08000;'>3</span>;i++ {
fmt.Println(inc.Increment())
}
}
<b>type</b> Writer2 <b>interface</b> {
Write([]<span style='color:#0057ae;'>byte</span>) (<span style='color:#0057ae;'>int</span>,<span style='color:#0057ae;'>error</span>)
}
<b>type</b> Closer2 <b>interface</b> {
Close() <span style='color:#0057ae;'>error</span>
}
<b>type</b> WriterCloser2 <b>interface</b>{
Writer2
Closer2
}
<b>type</b> myWriterCloser2 <b>struct</b> {
}
<b>func</b>(mwc myWriterCloser2) Write(data[] <span style='color:#0057ae;'>byte</span>) (<span style='color:#0057ae;'>int</span>,<span style='color:#0057ae;'>error</span>){
<b>return</b> <span style='color:#b08000;'>0</span>,<span style='color:#006e28;'>nil</span>
}
<b>func</b>(mwc myWriterCloser2) Close() <span style='color:#0057ae;'>error</span>{
<b>return</b> <span style='color:#006e28;'>nil</span>
}
<span style='color:#898887;'>// // {........}</span>
<span style='color:#898887;'>// Constructor</span>
<span style='color:#898887;'>// func NewconsoleWriterCloser() *consoleWriterCloser</span>
<span style='color:#898887;'>// {........}</span>
<b>func</b> part13_compose(){
fmt.Println(<span style='color:#bf0303;'>"part13_compose"</span>)
<span style='color:#898887;'>// all func( X myWriterCloser2)</span>
<b>var</b> wc WriterCloser2=myWriterCloser2{}
wc.Write([]<span style='color:#0057ae;'>byte</span>(<span style='color:#bf0303;'>"Hallo"</span>))
wc.Close()
fmt.Println(wc)
<span style='color:#898887;'>// all func( X myWriterCloser2) and func( X *myWriterCloser2)</span>
<b>var</b> pwc WriterCloser2=&myWriterCloser2{}
pwc.Write([]<span style='color:#0057ae;'>byte</span>(<span style='color:#bf0303;'>"Hallo"</span>))
pwc.Close()
fmt.Println(pwc)
<span style='color:#898887;'>//INTERFACE_CONVERSION_TO_ACCESS_INTERNAL_STRUCTURE</span>
<span style='color:#898887;'>// wc3:=wc.(*consoleWriterCloser)</span>
}
<b>func</b> part13_interfaces() {
part13_writer()
part13_incrementer()
part13_compose()
<span style='color:#898887;'>//empty interface , an interface with no methods, usefull for "type conversion"</span>
<b>var</b> ei <b>interface</b>{}
ei=<span style='color:#b08000;'>0</span>
<b>switch</b> ei.(<b>type</b>){
<b>case</b> <span style='color:#0057ae;'>string</span>:
fmt.Println(<span style='color:#bf0303;'>"ei is a string"</span>)
<b>case</b> <span style='color:#0057ae;'>int</span>:
fmt.Println(<span style='color:#bf0303;'>"ei is an integer"</span>)
}
ei=<span style='color:#bf0303;'>"alain"</span>
<b>switch</b> ei.(<b>type</b>){
<b>case</b> <span style='color:#0057ae;'>string</span>:
fmt.Println(<span style='color:#bf0303;'>"ei is a string"</span>)
<b>case</b> <span style='color:#0057ae;'>int</span>:
fmt.Println(<span style='color:#bf0303;'>"ei is an integer"</span>)
}
}
<b>func</b> sayHello(){
fmt.Println(<span style='color:#bf0303;'>"Hello"</span>)
}
<span style='color:#898887;'>// Concurrent en parallel programming , use of many cors</span>
<b>func</b> part14_alfa() {
fmt.Println(<span style='color:#bf0303;'>"part14_alpha"</span>)
<span style='color:#898887;'>//spin greenthread , no os thread but lightweigth thread </span>
<span style='color:#898887;'>// go routines are mapped to os threads , small stack spaces</span>
<b>go</b> sayHello() <span style='color:#898887;'>//spawned thread </span>
time.Sleep(<span style='color:#b08000;'>100</span>*time.Millisecond)
<span style='color:#898887;'>//anonymous</span>
<b>var</b> msg=<span style='color:#bf0303;'>"Hallo"</span>
<b>go</b> <b>func</b>() {
time.Sleep(<span style='color:#b08000;'>10</span>*time.Millisecond)
fmt.Println(msg) <span style='color:#898887;'>//prints goodbye ,race, bad idea</span>
}()
msg=<span style='color:#bf0303;'>"Goodbye"</span>
time.Sleep(<span style='color:#b08000;'>100</span>*time.Millisecond)
msg=<span style='color:#bf0303;'>"Hallo"</span>
<b>go</b> <b>func</b>(msg <span style='color:#0057ae;'>string</span>) {
time.Sleep(<span style='color:#b08000;'>10</span>*time.Millisecond)
fmt.Println(msg) <span style='color:#898887;'>//prints hallo ,ok , a copy of msg </span>
}(msg)
msg=<span style='color:#bf0303;'>"Goodbye"</span>
time.Sleep(<span style='color:#b08000;'>100</span>*time.Millisecond)
}
<b>var</b> wgb=sync.WaitGroup{} <span style='color:#898887;'>// object of type waitgroup {}</span>
<b>func</b> part14_beta() {
fmt.Println(<span style='color:#bf0303;'>"part14_beta"</span>)
msg:=<span style='color:#bf0303;'>"Hallo</span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>
wgb.Add(<span style='color:#b08000;'>1</span>) <span style='color:#898887;'>//add 1</span>
<b>go</b> <b>func</b>(msg <span style='color:#0057ae;'>string</span>) {
fmt.Println(msg) <span style='color:#898887;'>//prints hallo ,ok , a copy of msg</span>
wgb.Done() <span style='color:#898887;'>// substract 1</span>
}(msg)
msg=<span style='color:#bf0303;'>"Goodbye</span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>
wgb.Wait() <span style='color:#898887;'>//wait until 0</span>
msg=<span style='color:#bf0303;'>"Gedaan</span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>
}
<b>var</b> wg=sync.WaitGroup{} <span style='color:#898887;'>//global</span>
<b>var</b> counter=<span style='color:#b08000;'>0</span>
<span style='color:#898887;'>// lock, protects code</span>
<span style='color:#898887;'>// readwrite mutex, </span>
<span style='color:#898887;'>// - maximum one write at the same time</span>
<span style='color:#898887;'>// - if one is reading no one can write</span>
<span style='color:#898887;'>// - as many as possible read at the same time</span>
<b>var</b> m=sync.RWMutex{}
<b>func</b> sayHellog (){
fmt.Printf(<span style='color:#bf0303;'>"Hello #%v</span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,counter)
m.RUnlock() <span style='color:#898887;'>//Unlocks are done asynchronously</span>
wg.Done() <span style='color:#898887;'>// decrease the number of threads</span>
}
<b>func</b> increment(){
counter++
m.Unlock() <span style='color:#898887;'>//Unlocks are done asynchronously</span>
wg.Done() <span style='color:#898887;'>//decrease the number of threads</span>
}
<b>func</b> part14_gamma(){
fmt.Println(<span style='color:#bf0303;'>"part14_gamma"</span>)
fmt.Printf(<span style='color:#bf0303;'>"Threads available: %v </span><span style='color:#924c9d;'>\n</span><span style='color:#bf0303;'>"</span>,runtime.GOMAXPROCS(-<span style='color:#b08000;'>1</span>)) <span style='color:#898887;'>//8 os threads because of 8 cores</span>
<span style='color:#898887;'>// runtime.GOMAXPROCS(1) // eg to avoid race conditions</span>
runtime.GOMAXPROCS(<span style='color:#b08000;'>4</span>) <span style='color:#898887;'>// to map all go threads to 4 os threads </span>
<b>for</b> i:=<span style='color:#b08000;'>0</span>;i<<span style='color:#b08000;'>5</span>;i++{
wg.Add(<span style='color:#b08000;'>1</span>) <span style='color:#898887;'>// increase the number of threads</span>
m.RLock() <span style='color:#898887;'>// Locks are done in the main thread</span>
<b>go</b> sayHellog()
wg.Add(<span style='color:#b08000;'>1</span>) <span style='color:#898887;'>// increase the number of threads</span>
m.Lock() <span style='color:#898887;'>// Locks are done in the main thread </span>
<b>go</b> increment()
}
wg.Wait() <span style='color:#898887;'>// wait until all threads done</span>
}
<b>func</b> part14_goroutines() {
part14_alfa()
part14_beta()
part14_gamma()
}
<b>var</b> wgc=sync.WaitGroup{}
<span style='color:#898887;'>//to synchronise data between different go routines (threads)</span>
<b>func</b> part15_alfa(){
fmt.Println(<span style='color:#bf0303;'>"part15_alpha"</span>)
<span style='color:#898887;'>//a channel to send integers</span>
ch:=<span style='color:#644a9b;'>make</span>(<b>chan</b> <span style='color:#0057ae;'>int</span>) <span style='color:#898887;'>//int,datatype that flows through the channel</span>
<span style='color:#898887;'>//consumer of channel</span>
wgc.Add(<span style='color:#b08000;'>1</span>)
<b>go</b> <b>func</b>() {
i:= <- ch
fmt.Println(i)
i=<span style='color:#b08000;'>1111</span> <span style='color:#898887;'>//changes the copy</span>
wgc.Done()
}()
<span style='color:#898887;'>//provider of channel</span>
wgc.Add(<span style='color:#b08000;'>1</span>)
<b>go</b> <b>func</b>() {
ch <- <span style='color:#b08000;'>42</span> <span style='color:#898887;'>// copies the 42 before sending , arrow show direction of data flow</span>
wgc.Done()
}()
<span style='color:#898887;'>//Wait until both done</span>
wgc.Wait()
}
<b>func</b> part15_beta(){
fmt.Println(<span style='color:#bf0303;'>"part15_beta"</span>)
<span style='color:#898887;'>//a channel to send integers</span>
ch:=<span style='color:#644a9b;'>make</span>(<b>chan</b> <span style='color:#0057ae;'>int</span>)
<b>for</b> j:=<span style='color:#b08000;'>0</span>;j<<span style='color:#b08000;'>5</span>;j++ {
<span style='color:#898887;'>//consumer of channel</span>
wgc.Add(<span style='color:#b08000;'>1</span>)
<b>go</b> <b>func</b>() {
i:= <- ch
fmt.Println(i)
i=<span style='color:#b08000;'>1111</span> <span style='color:#898887;'>//changes the copy</span>
wgc.Done()
}()
<span style='color:#898887;'>//provider of channel</span>
wgc.Add(<span style='color:#b08000;'>1</span>)
<b>go</b> <b>func</b>() {
<span style='color:#898887;'>// copies the 42 before sending , arrow show direction of data flow</span>
<span style='color:#898887;'>// Note it block until the channel is free, the channel is unbuffered</span>
ch <- <span style='color:#b08000;'>42</span>
wgc.Done()
}()
}
<span style='color:#898887;'>//Wait until both done</span>
wgc.Wait()
}
<span style='color:#898887;'>// readwrite channel</span>
<b>func</b> part15_gamma(){
fmt.Println(<span style='color:#bf0303;'>"part15_gamma"</span>)
<span style='color:#898887;'>//a channel to send integers</span>
ch:=<span style='color:#644a9b;'>make</span>(<b>chan</b> <span style='color:#0057ae;'>string</span>)
<b>for</b> j:=<span style='color:#b08000;'>0</span>;j<<span style='color:#b08000;'>5</span>;j++ {
wgc.Add(<span style='color:#b08000;'>1</span>)
<b>go</b> <b>func</b>() {
ina:= <- ch
fmt.Println(ina)
ch <- <span style='color:#bf0303;'>"Second"</span>
wgc.Done()
}()
wgc.Add(<span style='color:#b08000;'>1</span>)
<b>go</b> <b>func</b>() {
ch <- <span style='color:#bf0303;'>"First"</span>
inb:= <- ch
fmt.Println(inb)
wgc.Done()
}()
}
<span style='color:#898887;'>//Wait until both done</span>
wgc.Wait()
}
<span style='color:#898887;'>//go routines, undirectional </span>
<b>func</b> part15_delta(){
fmt.Println(<span style='color:#bf0303;'>"part15_delta"</span>)
<span style='color:#898887;'>//a channel to send integers</span>
ch:=<span style='color:#644a9b;'>make</span>(<b>chan</b> <span style='color:#0057ae;'>string</span>)
wgc.Add(<span style='color:#b08000;'>1</span>)
<span style='color:#898887;'>//receive only channel</span>
<b>go</b> <b>func</b>(ch <- <b>chan</b> <span style='color:#0057ae;'>string</span>) { <span style='color:#898887;'>//cast of a bidirectional channel to a uniderectional</span>
ina:= <- ch
fmt.Println(ina)
<span style='color:#898887;'>//ch <- "Second" ,error</span>
wgc.Done()
}(ch)
wgc.Add(<span style='color:#b08000;'>1</span>)
<span style='color:#898887;'>//send only channel </span>
<b>go</b> <b>func</b>(ch <b>chan</b><- <span style='color:#0057ae;'>string</span>) {
ch <- <span style='color:#bf0303;'>"First"</span>