Learn to Program with C_ Learn to Program using the Popular C Programming Language ( PDFDrive )

7.7.1 Using Factorial
Chapter 7 ■ Functions
We illustrate how factorial can be used by writing a complete Program P7.7, which prints n!
for n = 0, 1, 2, 3, 4, 5, 6 and 7.
Program P7.7
#include <stdio.h>
int main() {
int factorial(int);
printf(" n n!\n\n");
for (int n = 0; n <= 7; n++)
printf("%2d %5d\n", n, factorial(n));
} //end main
int factorial(int n) {
int nfac = 1;
for (int h = 2; h <= n; h++)
nfac = nfac * h;
return nfac;
} //end factorial
When run, this program prints the following:
n n!
0 1
1 1
2 2
3 6
4 24
5 120
6 720
7 5040
As you can see, the value of factorial increases very quickly. Even 8! = 40320, which is too big
to fit in a 16-bit integer (largest value that can be stored is 32767). As an exercise, write the loop
from 0 to 8 and see what happens.
Let us take a closer look at main. The first statement is the function prototype for factorial.
This is needed since factorial will be called from main.
181
www.it-ebooks.info