C++ Tutorial: Compile and Run

Programming in C++ in the Lab

(Or Compiling and Executing Programs from the Command Line)

As previously mentioned in the Getting Started guide, you will be writing your program in C++ using sublime, a simple text editor for Linux.

If you have not already opened sublime, do so now. Then for each program you write for the tutorial, follow these instructions:

1. Copy the input provided, if any, and paste it into a new file in the editor.
2. Save your file.
   • Go to File > Save As...
   • If this is your first time to save a program as part of the tutorial, create a new folder somewhere within your home directory structure:
     1. Click on your username in the lefthand panel (for example, horns180).
     2. Click the Create Folder button, and name it something exciting and descriptive, like Tutorial.
     3. Hit Enter.
     4. If you choose, you may further organize your individual tutorial programs into their own directories---we leave it up to you.
   • Give your file a descriptive name with a file type of .cpp. For example, for your first program, you might name the file HelloWorld.cpp. Among other things, the .cpp will tell sublime that the content of this file is C++ code, and it will enable related editing features. Hit Save when you are happy with your file name.
   • Linux does not handle spaces in file names or directory/folder names well, so if you use a space you will need to escape it whenever you access that file or directory. For example, if you name a file "Hello World.cpp", you will need to type "Hello\ World.cpp". We recommend "HelloWorld.cpp" or "Hello_World.cpp" instead.
3. Add your code.
4. Compile your code.
   • Compiling is converting it from the (sort of) English version you typed into the language understood by the machine (which is all 0s and 1s).
   • The output of a successful compilation will be an executable file. This is what you will use to run, or execute, your program.
   • To compile, do the following:
     1. Make sure your files are saved!
     2. Open a new terminal window by clicking on the terminal icon again.
     3. Navigate to the directory where you saved your file using the commands we talked about here under Linux Commands.
     4. Once you're in the same directory as your file, begin typing in the following:

        g++ <filename> -o <executableName>
        

     5. Replace <filename> with the name of the file you have been editing, and replace <executableName> with something similarly descriptive. For example, for your HelloWorld program, you might compile with the following:

        g++ HelloWorld.cpp -o HelloWorld

   • Check the output in the terminal to see if the build was a success. If it was not, one or more errors will be printed to the terminal. See if you can understand and then fix the given errors. If you can't, please ask us! Compiler errors are famously hard to decipher.
5. Run your program.
   • Here's where the executable comes in! Still in your terminal, in the same directory as your program files, type in the following:

     ./executableName

     Replace executableName with the name you gave your executable when you compiled. Using the above example, to run your HelloWorld program you would enter ./HelloWorld at the command line.

   • Hit Enter to run the command.
   • Output from the execution will be printed to the terminal.
6. Many things can go wrong when you are programming, so please ask for help before you get frustrated! (Just turn your cups to red!)