58 lines
1.1 KiB
C
58 lines
1.1 KiB
C
/*
|
|
file name: factorUsingIterative.c
|
|
Description: Factorial numbers count using iterative
|
|
利用迴圈做N階乘的計算
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <ctype.h>
|
|
#include <stdlib.h>
|
|
|
|
/* 函數原型宣告 */
|
|
long Factorial(long);
|
|
void flushBuffer(void);
|
|
|
|
int main()
|
|
{
|
|
char ch;
|
|
long n;
|
|
|
|
printf("-----Factorial counting using Iterative-----");
|
|
do {
|
|
printf("\nEnter a number(0 <= n <= 12) to count n!: ");
|
|
scanf("%ld",&n);
|
|
flushBuffer();
|
|
if (n < 0 || n > 12)
|
|
printf("Input out of range!\n");
|
|
else
|
|
printf("%ld! = %ld\n", n, Factorial(n));
|
|
|
|
printf("Continue(y/n)? ");
|
|
ch = toupper(getchar());
|
|
} while (ch == 'Y');
|
|
|
|
return 0;
|
|
}
|
|
|
|
long Factorial(long n)
|
|
{
|
|
long sum = 1;
|
|
int i;
|
|
|
|
if (n == 0 || n ==1) /* 當 n=0 或 n=1 時, 0!=1, 1!=1 */
|
|
return (1); /* 故直接傳回1 */
|
|
else {
|
|
for (i = 2; i<= n; i++) /* sum 記錄目前階乘之和 */
|
|
sum *= i; /* sum 與 i 相乘之和放回 sum 中 */
|
|
}
|
|
return (sum);
|
|
}
|
|
|
|
void flushBuffer()
|
|
{
|
|
while (getchar() != '\n') {
|
|
continue;
|
|
}
|
|
}
|
|
|