编写函数把华氏温度转换为摄氏温度，公式为：C = (F

#include<iostream>
using namespace std;
float centigrade(float a)
{
float b;
b=5.0/9.0*(a-30);
return int(b);
}
int main()
{
float x;
cout<<"请输入华氏温度:"<<endl;
cin>>x;
cout<<"摄氏温度为："<<centigrade(x)<<endl;
return 0;
}