c++初学者求助！
如图！下面是我写的计算加减乘除的程序，求大神帮忙指点我的错误！感谢！
#include<iostream>
using namespace std;
void main() {
double x,y;
char op;
cout<<"请选择你想计算的运算符（+ - * /）:";
cin>>op;
if(op='+'){
cout<<"请输入两个数字:";
cin>>x>>y;
cout<<"z="<<x<<"+"<<y<<"="<<x+y<<endl;
}
else if(op=='-')
cout<<"请输入两个数字:";
cin>>x>>y;
cout<<"z="<<x<<"-"<<y<<"="<<x-y<<endl;
}
else if(op=='*')
cout<<"请输入两个数字:";
cin>>x>>y;
cout<<"z="<<x<<y<<"*"<<"="<<x*y<<endl;
}
else if(op=='/')
cout<<"请输入两个数字:";
cin>>x>>y;
if(y<1e-6&&-y<1e-6){
cout<<"除数为0"<<endl;
}
else{
cout<<"z="<<x<<y<<"/"<<"="<<x/y<<endl;
}
}else{
cout<<"不支持该运算:"<<op<<endl;
}
}