我如何使用tryparse？ [英] How do I use tryparse ?

问题描述

我希望用户必须填写邮政编码。邮政编码包含4位数字，如果邮政编码包含更多或更少的数字，则代码将显示错误

I want that the user must fill in a zip code.The Zip code contains 4 digits if the zip code has more or less digits then the code will indicate an error

    Console.Write("Geef je postcode: ");
    postcode =  Console.ReadLine();


while (int.TryParse(postcode, out))// i want that if the zip code has more or less than 4 digits then it will give the code in the while.
{

    Console.WriteLine("ongeldige postcode");
    Console.WriteLine("Geef je postcode: ");
    postcode = Console.ReadLine();
}

我尝试过：

What I have tried:

while (int.TryParse(postcode, out))

但我不知道如何使用tryparse。

but i don't know how to use tryparse.

推荐答案

Tryparse尝试从一种类型转换到另一种类型，它不测试长度。



邮政编码是一个字符串，所以使用.Length来测试<> 4.

Tryparse attempts a conversion from one type to another, it does not test the length.

postcode is a string so use the .Length to test <> 4.

while (postcode.Length != 4)// i want that if the zip code has more or less than 4 digits then it will give the code in the while.
{
 
    Console.WriteLine("ongeldige postcode");
    Console.WriteLine("Geef je postcode: ");
    postcode = Console.ReadLine();
}

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