The C Preprocessor
The C preprocessor is a program that processes a C source file before the compiler translates the program into object code. During processing the C source file, it performs certain modifications on the file based upon instructions or directives to the preprocessor. The preprocessor directives are simply commands that start with a # symbol (character). We will examine these directives one by one in this chapter.
9.1 | MACRO SUBSTITUTION
We have already seen that the #define preprocessor directive is used to create a symbolic constant for use in a program. The general form of this directive is given by:
#define macro-name replacement—text
where macro-name is replaced with replacement–text through the program.