C Primer Plus®, Third Edition

While You're at It…Multiple Functions

So far, these programs have used the standard printf() function. Listing 2.3 shows you how to incorporate a function of your own—besides main()—into a program.

Listing 2.3 The two_func.c program.

/* two_func.c -- a program using two functions in one file */ #include <stdio.h> void butler (void); /* ANSI C function prototyping */ /* pre-ANSI C uses void butler(); instead */ int main(void) { printf(I will summon the butler function.\n); butler(); printf(Yes. Bring me some tea and writeable CD-ROMS.\n);[sr] return 0; } void butler(void) /* start of function definition */ { printf("You rang, sir?\n"); }

The output looks like this:

 I will summon the butler function. You rang, sir? Yes. Bring me some tea and ...