换成double后输出全为0.00了，没明白为什么

Question

#include<stdio.h>#include<math.h>void fir(double x); void scd(double x);int main(){  float  x;//这里能换成 double x 吗？为什么   scanf("%f",&x);  if(x>=0)  fir(x);  else  scd(x);  return 0;}void fir(double x){ double b;  b=sqrt(x);    printf("f(%.2f)=%.2f",x,b);}void scd(double x){ double b;  b=pow(x+1,2);  printf("f(%.2f)=%.2f",x,b);}

Answer 1

你换成double的话，输入应该是

scanf("%lf",&x);

%lf代表double， %f代表float