How To Compile from the Command Line

Often, it is useful to compile a a simple program from the command line. The steps to do so are listed below.

• Create a folder to contain your source code and executable. For labs and homework assignments, create a folder on the Desktop and name the folder as CS120Assignment#YourName with no spaces. As an example, CS120Lab1JaneDoe.
• Open the Command Prompt program which can be found from in the Doc - resembles a black window.
• Navigate to the folder you created on the Desktop. You will do this within the Command Prompt window by using the "cd" command (cd stand for change directory). The easiest way to do this is to type "cd " at the command line and then drag your folder onto the Command Prompt window. You should see a prompt similar to the one below:

  tag4622:~ labuser$ cd /Users/labuser/Desktop/CS120Lab1JaneDoe

• You can list the contents of your current directory within the Command Prompt window by typing "ls" (ls stands for list directory).
• Create your source program using TextWrangler. Save the source program - If you are creating a C source file the program should be named with a .c extension. If the file is a header file it must be named with a .h extension. If the file is C++ source it should be named with the .cpp extension. Be sure to save the file in the folder you created on the Desktop.
• To compile a single C++ source file, type in the following command within the Command Prompt window:

  g++ -o Lab1 Lab1.cpp

  Here, g++ invokes the C++ compiler, the -o option specifies the name of the created object file (the executable is Lab1 for this example), and Lab1.cpp is the source file to be compiled. You should see a prompt similar to the one below:

  tag4622:~ CS120Lab1JaneDoe$  g++ -o Lab1 Lab1.cpp

• If your source file compiles without errors then you should find an executable file located in your directory. You can check this by typing "ls" to list the directory contents.
• To run your program type "./name of the executable file" at the Command Prompt. You should see a prompt similar to the one below:

  tag4622:~ CS120Lab1JaneDoe$ ./Lab1

• For more information on compiling multiple files or using advanced compiler options type "man g++" in the Command Prompt window to see the manual pages for the g++ compiler.