才学C 做了阶乘用不了。。。。帮帮看看哪里错了555

#include<stdio.h> double jie(double b); void main() { double a=0,h=0; printf("input",a); scanf("%f",&a); h=jie(a); printf("%.0f\n",h); } double jie(double b) { double i,j=1; for(i=1;i<b;++i) j*=i; return(j); }