C ++检查数字是否为int/float

问题描述

我是新来的.我在Google上找到了这个网站.

i'm new here. i found this site on google.

#include <iostream>

using namespace std;

void main() {

    // Declaration of Variable
    float num1=0.0,num2=0.0;

    // Getting information from users for number 1
    cout << "Please enter x-axis coordinate location : ";
    cin >> num1;

    // Getting information from users for number 2
    cout << "Please enter y-axis coordinate location : ";
    cin >> num2;

    cout << "You enter number 1 : " << num1 << " and number 2 : " << num2 <<endl;

我需要类似的内容，当用户输入字母字符时，它会显示错误信息，提示您应该输入数字.

I need something like, when users enter alphabetical characters, it would display an error says, you should enter numbers.

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推荐答案

首先，回答您的问题.这实际上非常容易，您不需要在代码中进行太多更改:

First, to answer your question. This is actually very easy and you don't need to change much in your code:

cout << "Please enter x-axis coordinate location : " << flush;
if (!(cin >> num1)) {
    cout << "You did not enter a correct number!" << endl;
    // Leave the program, or do something appropriate:
    return 1;
}

此代码基本上检查输入是否被有效地解析为浮点数-如果未发生，则表示错误.

This code basically checks whether the input was validly parsed as a floating point number – if that didn't happen, it signals an error.

第二， main 始终的返回类型必须始终是 int ，而不是 void .

Secondly, the return type of main must always be int, never void.

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