Question

我有这个程序：

#include <iostream>

using namespace std;

int calculateResultAndPrintIt(int firstNr, char operand, int secondNr)
{
    int sum = 0;
    if(operand == '+')
        sum = firstNr + secondNr;

    else if(operand == '-')
        sum = firstNr - secondNr;

    else if(operand == '*')
        sum = firstNr * secondNr;

    else if(operand == '/')
        sum = firstNr / secondNr;

    else
    {
        cout << "Invalid operation! Returning!";
        return -1;
    }

    cout << firstNr << " " << operand << " " << secondNr << " is " << sum << endl;
    return 0;
}

int main(void)
{
    int firstNr = 0;
    char operand = '+';
    int secondNr = 0;

    cout << "Enter a value: ";
    cin >> firstNr;

    cout << "Enter a second value: ";
    cin >> secondNr;

    cout << "Enter one of the following: +, -, *, or /: ";
    cin >> operand;

    int back = calculateResultAndPrintIt(firstNr, operand, secondNr);

    if(back != 0)
        return -1;
    else
        return 0;
}

当它询问我“输入一个值：”或“输入第二个值：”然后我输入类似'l'的内容然后它显示如下：

输入一个数字：l 输入第二个值：输入以下值之一：+， - ，*或/：0 + 0为0

但我想要的是我可以显示消息“不是整数！”当用户输入一个角色时！像：

输入一个数字：l 不是整数！

Answer 1

致电cin后，请检查：

if (!cin)
{
    cout << "Not an integer!" << endl;
}

或者，cin在输入不匹配时设置称为failbit的内容。您可以使用cin.fail()

进行测试

如何检测错误的数据类型？

1 个答案: