C++ Primer, Fifth Edition

6.1.3. Separate Compilation

As our programs get more complicated, we’ll want to store the various parts of the program in separate files. For example, we might store the functions we wrote for the exercises in § 6.1 (p. 205) in one file and store code that uses these functions in other source files. To allow programs to be written in logical parts, C++ supports what is commonly known as separate compilation. Separate compilation lets us split our programs into several files, each of which can be compiled independently.

Compiling and Linking Multiple Source Files

As an example, assume that the definition of our fact function is in a file named ...