CS50 Library for C

Intro

This is CS50's Library for C... but for Windows!

You will need a C compiler already installed on your machine for this to work.

I personally use GCC (gcc.exe) and GNU Make (make.exe) as built for Windows by MSYS2.

LLVM Clang (clang.exe) also works for building this library.

I've also tested this with Microsoft Visual C/C++ Compiler (MSVC, cl.exe) which you can get by installing Visual Studio.

From here on I'll be referring to the Visual Studio tools as MSVC.

• You can install either the Visual Studio IDE or the Visual Studio Build Tools.

• I personally went with Visual Studio Build Tools 2019, which is what I'll be using for the MSVC portion of this document.

Lastly, make sure your compiler of choice is already in your PATH environment variable! This makes is so that you don't have to remember the exact place you installed it in every time you want to use it from the command line.

This, in turn, allows you simply type, say, gcc.exe and immediately get to work.

Installation

Installation will be directly from the command line. For GCC/Clang, you can simply use the normal Command Prompt, or use PowerShell. Your choice!

Normally, when building with MSVC, you have 2 options:

1. Run Developer Command Prompt For VS from the Start Menu and cd to the directory you downloaded this library to.

2. Locate your vcvarsall.bat file from your installation of Visual Studio, and run that directly in your terminal with 1 argument: your machine's architecture. For example, since I have Visual Studio Build Tools 2019, I can run it like so:

    C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Auxiliary\Build\vcvarsall.bat x64
   

• Do note because vcvarsall.bat is a Windows batchfile, it only really works for Command Prompt. Running it in PowerShell will not set things up properly.

This means that MSVC really only works from Command Prompt.

However, you can just run msvcbuild.bat, assuming you configured the VS_INSTALL variable to refer to your Visual Studio installation folder. You can run the batchfile in either Command Prompt or PowerShell and it should just work!

Environment Variables

Before you build the library, you'll need to set a few Environment Variables that are specifically used by GCC or those specifically used by MSVC.

If you're unfamiliar with working with environment variables:

1. Go to the Start Menu.

2. Type Edit the system environment variables.

3. Open the suggestion that pops up, it should have Control Panel in its name.

4. In the newly opened window, click Environment Variables...

5. When there, you can see so-called User variables and System variables.

6. To create a new environment variable, click the New button for either the User or System group. If you're unsure with which one to go with, I would recommend adding to the User group.

7. Enter the desired Variable name with your desired Variable value, for example:

    Variable name: C_INCLUDE_PATH
    Variable value: C:\libcs50-windows\src
   

8. To edit existing environment variables, click the variable first then click the Edit button.

9. You can then add values to this variable by clicking the New button, such as for the Path environment variable.

10. Repeat this process for the other environment variables that your compiler needs! See the below sections for more information.

Note! In order for changes to system variables to take effect, you need to restart the terminal you're working on.

GCC/Clang

C_INCLUDE_PATH: Tells the C compiler where to find header (.h) files.

LIBRARY_PATH: Tells the linker where to find import library (.a) files.

Examples:

Variable name: C_INCLUDE_PATH
Variable value: C:\libcs50-windows\src

Variable name: LIBRARY_PATH
Variable value: C:\libcs50-windows\lib

For more information, try compiling a dummy project like so:

gcc -xc -v dummy.c

then look for the lines #include <...> search starts here and LIBRARY_PATH to see if your environment variables were added properly!

Visual Studio (MSVC)

INCLUDE: Tells the MSVC compiler where to find header (.h) files.

LIB: Tells the MSVC linker where to find import library (.lib) files.

Examples:

Variable name: INCLUDE
Variable value: C:\libcs50-windows\src

Variable name: LIB
Variable value: C:\libcs50-windows\lib

DLL Path

This one's specific to Windows and independent of any compiler. Basically, Windows has a specific set of rules when it comes to determing where to look for DLLs. For our purposes, the most important are these 2:

1. DLLs must be located in the same directory as the executable.

This means that if I ran this command:

gcc hello.c -lcs50 -o hello.exe

If Windows can't find cs50.dll in the same directory as hello.exe, the created application won't run! You could fix this by simply copying cs50.dll everywhere you need it, and that would work.

But that defeats the point of having this library in one place, doesn't it?

2. Add the path containing cs50.dll to your PATH environment variable.

Yep, more environment variables. Don't worry, I assure you this is the last!

If you need a refresher, refer to this section.

Chances are your PATH variable already exists, so you'll just need to add the folder containing cs50.dll to it.

For example, if you downloaded this library to the C:\ drive, then you just need to add C:\libcs50-windows\bin to PATH.

So if I run the previous build command, now Windows knows to also look in C:\libcs50-windows\bin for the file cs50.dll. Once it finds that, the program we created should run!

Actually Building

make: if you have a version of make installed, simply running the command make in the directory will automatically build the library for you!

• You can also change the variable CC to be gcc, clang or whatever you may have installed.

• If you're going to use Visual Studio, consider using msvcbuild.bat instead!

msvcbuild.bat: similar to make, but using Visual Studio/MSVC.

• Before you run this, be sure to change the VS_INSTALL variable inside of the batchfile to the correct path of your Visual Studio installation, be it the IDE or the Build Tools.

• Or, if you prefer, simply open Developer Command Prompt For VS (year) and cd to the library's directory, then run the batchfile!

For MSVC, you may get errors like these:

src\cs50.c(159): warning C4244: '=': conversion from 'int' to 'char', possible loss of data

src\cs50.c(237): warning C4996: 'sscanf': This function or variable may be unsafe. Consider using sscanf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

This is normal, it just means the CS50 Library itself uses some techniques or functions that, when looked at very very strictly, may be considered bad practice.

Assuming you're just using the library for personal use, these warnings shouldn't matter all that much to you.

However, if you're considering using this library in a real-world project, consider using a different library! The CS50 Library is intended more as "training wheels" for the CS50 course!

Usage

For GCC/Clang, link with the flag -lcs50, for example:

gcc.exe hello.c -lcs50

For MSVC, simply add cs50.lib after your source file/s. For example:

cl.exe hello.c cs50.lib

If you set the correct environment variables for your respective compiler, then it should link properly!

General usage:

#include <cs50.h>

...
char c = get_char("Prompt: ");
double d = get_double("Prompt: ");
float f = get_float("Prompt: ");
int i = get_int("Prompt: ");
long l = get_long("Prompt: ");
string s = get_string("Prompt: ");

// deprecated as of fall 2017
long long ll = get_long_long("Prompt: ");

Cleaning

To remove all the build files, simply run your build script on choice in the command line followed by the word clean, for example:

make clean

Or:

msvcbuild.bat clean

This will remove all the build files but keep the bin\, obj\ and lib\ folders around.

Uninstalling

If you also want to remove the build files and the folders, simply use uninstall instead of clean, for example:

make uninstall

Or:

msvcbuilt.bat uninstall

Afterwards, you may also want to clear the environment variables you set for the compiler. You can then remove the folder from your machine.

Do note that because my Makefile is intended to be used on either Command Prompt or PowerShell, I opted not to use shell-specific commands to check if folders exist already, because a command like if exist bin\ rmdir bin\ will only work on Command Prompt, but not on PowerShell.

Documentation

See CS50 Reference!

Original CS50 Library Contributors

• Chad Sharp
• Emrul Hasan Zawad
• Ivan Jasenov
• Kareem Zidane