C ++字符到int [英] C++ character to int

问题描述

当你把字母变成int变量时会发生什么？我试着简单的代码添加2个int数字，首先阅读它们，而不是添加它们。但是当我进入信件，它只是失败，打印吨数字屏幕。但是什么原因导致这个错误？我的意思是，我希望它加载和使用该信的ASCII码。

what happens when you cin>> letter to int variable? I tried simple code to add 2 int numbers, first read them, than add them. But when I enter letter, it just fails and prints tons of numbers to screen. But what causes this error? I mean, I expected it to load and use ASCII code of that letter.

推荐答案

我假设你有这样的代码：

I assume you have code like this:

int n;
while (someCondition) {
    std::cin >> n;
    .....
    std::cout << someOutput;
}

当输入不能读为整数的内容时， :: cin）进入失败状态，并且只要您不处理输入错误，所有后续输入尝试都会失败。

When you enter something that cannot be read as an integer, the stream (std::cin) enters a failed state and all following attempts at input fail as long as you don't deal with the input error.

您可以测试输入操作：

if (!(std::cin >> n)) //failed to read int

，您可以将流恢复到正常状态并丢弃未处理的字符（导致输入失败的输入） ：

and you can restore the stream to a good state and discard unprocessed characters (the input that caused the input failure):

std::cin.clear();
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

另一种可能性是接受输入到字符串变量（很少失败），并尝试转换字符串到int。

Another possibility is to accept input into a string variable (which rarely fails) and try to convert the string to int.

这是一个非常常见的输入问题，在这里和其他地方应该有很多线程。

This is a very common problem with input and there should be tons of threads about it here and elsewhere.

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