maps.cpp

#include <iostream>
#include <map>
using namespace std;
int main(){
    map <char,int> mp;
    map <char,int> mymap,mymap1;

    //insert elements individually in map with the combination of key value and value of element
    mp.insert(pair<char,int>('a',2));   //key is 'c' and 2 is value.
    mp.insert(pair<char,int>('b',1));
    mp.insert(pair<char,int>('c',43));

    //inserts elements in range using insert() function in map 'mymap'.
    mymap.insert(mp.begin(),mp.end());

    //declaring iterator for map
    map <char,int>::iterator it;

    //using find() function to return reference of element mapped by key 'b'.
    it = mp.find('b');

    //prints key and element's value.
    cout<<"Key and element's value of map are: ";
    cout<<it->first<<" and "<<it->second<<endl; // it->first will print the key and it->second will print the value
    

    //alternative way to insert elements by mapping with their keys.
    mymap1['x'] = 23;
    mymap1['y'] = 21;

    cout<<"Printing element mapped by key 'b' using at() function : "<<mp.at('b')<<endl;

    //swap contents of 2 maps namely mymap and mymap1.
    mymap.swap(mymap1);

    /* prints swapped elements of mymap and mymap1 by iterating all the elements through    
        using   iterator. */
    cout<<"Swapped elements and their keys of mymap are: "<<endl;
    for(it=mymap.begin();it!=mymap.end();it++)
    {
    cout<<it->first<<" "<<it->second<<endl;
    }
    cout<<"Swapped elements and their keys of mymap1 are: "<<endl;
    for(it=mymap1.begin();it!=mymap1.end();it++)
    {
    cout<<it->first<<" "<<it->second<<endl;
    }
    //erases element mapped at 'c'.
    mymap1.erase('c');

    //prints all elements of mymap after erasing element at 'c'.

    cout<<"Elements of mymap1 after erasing element at key 'c' : "<<endl;
    for(it=mymap1.begin();it!=mymap1.end();it++)
    {
    cout<<it->first<<" "<<it->second<<endl;
    }

    //erases elements in range from mymap1
    mymap1.erase(mymap1.begin(),mymap1.end());

    cout<<"As mymap1 is empty so empty() function will return 1 : " << mymap1.empty()<<endl;

    //number of elements with key = 'a' in map mp.
    cout<<"Number of elements with key = 'a' in map mp are : "<<mp.count('a')<<endl;

    //if mp is empty then itmp.empty will return 1 else 0.
    if(mp.empty())
    {
        cout<<"Map is empty"<<endl;
    }
    else
    {
        cout<<"Map is not empty"<<endl;
    }

    return 0;
}