怎样用C语言算出1！+2！+3！+4！+5！

long jiecheng(short num)
{long result=1;
if (num<1)
return -1;
else
{
for (int j=1,j<=num,j++)
result*=j;
return result
}
}

int main()
{
long answer=0;
long jiecheng(short);

for (short i=1;i<6;i++)
answer+=jiecheng(i);
}

用FOR循环做举例5!
for(i=1;i<=5;i++)
{
s=s*i;(s初值为1)
}

main(){
int i,sum=0;
int n=1;
for(i=1;i<6;i++)
{n=n*i;
sum+=n;
}
printf("1!+2!+3!+4!+5!=%d",sum);
}