从C＃中的控制台读取整数时出错 [英] Error While reading integer from console in C#

问题描述

你好专家，



首先，到目前为止所有帮助都是thx。现在我有一个小问题，但我需要一些建议。

Hello experts,

First of all, thx for all the help so far. Now i have a small issue but i need some suggestions.

int option;  option = Convert.ToInt32(Console.ReadLine());

如果我输入一个0-9的数字，一切都很好，但是如果我输入一个错误的信件。有什么建议吗？

If i enter a number from 0-9 all works great, but if i enter a letter an error promts. Any suggestions pls?

推荐答案

而不是Convert.ToInt32，你应该使用Int32.TryParse。

Instead of Convert.ToInt32, you should use Int32.TryParse instead.

int option;
string inValue = Console.ReadLine();
if( Int32.TryParse(inValue, out option) )
{
   // It converted successfully
}
else
{
   // Apply some default value or prompt the user that an invalid value was entered.
}

代码工作正常。除非你知道输入是一个int，否则Convert.ToInt32是无用的。否则，获取值并使用int.TryParse。

The code is working fine. Convert.ToInt32 is useless unless you KNOW the input is an int. Otherwise, get the value and use int.TryParse.

我有一些辅助扩展函数，如：

I have some helper extension functions like:

public static class Extensions
{
    /// <summary>Tries to parse a numeric value from this string.</summary>
    /// <remarks>In case of error, takes the given defaultValue.</remarks>
    /// <param name="defaultValue">Fallback in case of not matching input.</param>
    /// <returns>the parsed value or, in case of parsing errors, the defaultValue</returns>
    public static int ToInt(this string s, int defaultValue)
    {
        int value = int.TryParse(s, out value) ? value : defaultValue;
        return value;
    }
    /// <summary>Tries to parse a numeric value from this string.</summary>
    /// <remarks>In case of error, takes the given defaultValue.</remarks>
    /// <param name="defaultValue">Fallback in case of not matching input.</param>
    /// <returns>the parsed value or, in case of parsing errors, the defaultValue</returns>
    public static double ToDouble(this string s, double defaultValue)
    {
        double value = double.TryParse(s, out value) ? value : defaultValue;
        return value;
    }
    ...
}

要像这样使用：

To be used like this:

int option = Console.ReadLine().ToInt(1234);

干杯

Andi

Cheers
Andi

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