Today I am going to tell you about functions. Functions are a set of instructions that can be used over and over. Each function has 1 job. void main ( ) is the only function that is in every single program no matter what. A function prototype tells what variable is going to return. In this case, the variable in the prototype is a float, which means a decimal number is going to return. A peramiter is information to give to the function. The peramiter holds a set of instructions for the . The function prototype goes before main, because if it goes after, the computer would not know what sphere, the name, meant. Here is a function example.
/* sphere.c */
#include <stdio.h> /* Include header file for printf. */
#define PI 3.141592654 /* Define a constant. */
float sphere( int rad ); /* Function prototype. */
void main() /* Main program. */
{
float vol; /* Declare variable. */
int radius = 3; /* Declare and initialize variable. */
vol = sphere( radius ); /* Call function, get result, print it. */
printf( "Volume: %f\n", vol );
}
float sphere( int rad ) /* Function. */
{
float result; /* Local variable declaration. */
result = rad * rad * rad;
result = 4 * PI * result / 3; return( result ); /* Result returned to main program. */
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