#include <stdio.h>
int main()
{
int n, i;
unsigned long long factorial = 1;
// 如果输入是负数,显示错误
if (n < 0)
printf("Error! 负数没有阶乘jiechen");
else
{
for(i=1; i<=n; ++i)
{
factorial *= i; // factorial = factorial*i;
}
printf("%d! = %llu", n
, factorial
); }
return 0;
}
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