//while写法
#include <stdio.h>
main()
{
long total=1, i=1;
while(i<=20)
{
total = total * i;
i++;
}
printf("result=%d\n", total);
}
//do-while写法
#include <stdio.h>
main()
{
long total=1, i=1;
do
{
total = total * i;
i++;
} while(i<=20);
printf("result=%d\n", total);
}
//for写法
#include <stdio.h>
main()
{
long total=1, i;
for(i=1; i<=20; i++)
total = total * i;
printf("result=%d\n", total);
}