编写一个函数求平方根，如果输入的是负数，抛出自定义类型的异常。如

squareErr

#pragma once
#include <stdexcept>
using namespace std;

class squareErr : public exception
{
public:
    squareErr();
    ~squareErr();
    const char *what() const;
};

squareErr.cpp

#include "stdafx.h"
#include "squareErr.h"
#include <iostream>
using namespace std;

squareErr::squareErr()
{
}

const char * squareErr::what() const{
    return "平方根参数不能为负";
}

squareErr::~squareErr()
{
}

main.cpp

// 异常处理-23期-92-子羽.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <stdexcept>
#include "squareErr.h"
#include <cmath>
using namespace std;

float square(float num) {
    if (num < 0)
    {
        throw squareErr();
    }
    return sqrt(num);
}

int _tmain(int argc, _TCHAR* argv[])
{
    try
    {
        square(-10);
    }
    catch (squareErr ex)
    {
        cout << ex.what() << endl;
    }

    return 0;
}