The Process

C++ is a compiled language. That means that to get a program to run, you must first translate it from the human-readable form to something a machine can “understand.” That translation is done by a program called a compiler.

What you read and write is called source code (usually it’s in an English-like language like C++), and what the computer executes is called executable, object code, or machine code (a machine language).

Typically C++ source code files are given the suffix:

  • .cpp (ex: hello.cpp) or
  • .h (ex: std_lib_facilities.h).

Compile:

g++ hello.cpp -o hello

A compiler translates the C++ program into machine language code which it stores on the disk as a file with the extension .o (e.g. hello.o). A linker then links the object code with standard library routines that the program may use and creates an executable image which is also saved on disk, usually as a file with the file name without any extension (e.g. hello).

Execute:

./hello

The executable is loaded from the disk to memory and the computer’s CPU (Central Processing Unit) executes the program one instruction at a time.

Running Hello World Locally:

On the Mac, it’s called the Terminal. On Windows, it’s called the Command Prompt.

Video Tutorials:

Compiling (xkcd)

xkcd: Compiling