第16周项目1异常处理求平方根

#include <iostream>#include <cmath>using namespace std;double squareroot(double &a){    double n;    if(a>=0)    n=sqrt(a);    else        throw a;    return n;}int main(){    double m;    try    {        cout<<"请输入一个需开方的数："<<endl;        cin>>m;        cout<<m<<"的平方根为"<<squareroot(m)<<endl;    }    catch(double)    {        cout<<"输入的数为负数，无法开方！"<<endl;    }    return 0;}