如何在C＃中检查字符串是否包含字符？ [英] How can I check if a string contains a character in C#?

问题描述

我是否可以对字符串应用一个函数，如果字符串包含字符，该函数将返回true或false。

Is there a function I can apply to a string that will return true of false if a string contains a character.

我的字符串带有一个或多个字符选项，例如：

I have strings with one or more character options such as:

var abc = "s";
var def = "aB";
var ghi = "Sj";

例如，我想做的是有一个函数，如果上面的函数返回true或false

What I would like to do for example is have a function that would return true or false if the above contained a lower or upper case "s".

if (def.Somefunction("s") == true) { }

在C＃中，我还需要检查是否为真，或者我可以删除 == true？

Also in C# do I need to check if something is true like this or could I just remove the "== true" ?

推荐答案

您可以使用扩展方法 .Contains（） 。 Linq：

You can use the extension method .Contains() from the namespace System.Linq:

using System.Linq;

    ...

    if (abc.ToLower().Contains('s')) { }

并且不，要检查布尔表达式是否为真，您不需要 == true

And no, to check if a boolean expression is true, you don't need == true

由于 Contains 方法是扩展方法，所以我的解决方案似乎有些困惑。这是两个版本，不需要您使用System.Linq添加； ：

Since the Contains method is an extension method, my solution appeared to be confusing to some. Here are two versions that don't require you to add using System.Linq;:

if (abc.ToLower().IndexOf('s') != -1) { }

// or:

if (abc.IndexOf("s", StringComparison.CurrentCultureIgnoreCase) != -1) { }

更新

如果愿意，您可以编写自己的扩展方法以方便重用：

If you want to, you can write your own extensions method for easier reuse:

public static class MyStringExtensions
{
    public static bool ContainsAnyCaseInvariant(this string haystack, char needle)
    {
        return haystack.IndexOf(needle, StringComparison.InvariantCultureIgnoreCase) != -1;
    }

    public static bool ContainsAnyCase(this string haystack, char needle)
    {
        return haystack.IndexOf(needle, StringComparison.CurrentCultureIgnoreCase) != -1;
    }
}

然后您可以这样称呼他们：

Then you can call them like this:

if (def.ContainsAnyCaseInvariant('s')) { }
// or
if (def.ContainsAnyCase('s')) { }

在大多数情况下，用户数据，您实际上想使用 CurrentCultureIgnoreCase （或 ContainsAnyCase 扩展方法），因为这样可以让系统处理取决于语言的大写/小写问题。处理诸如HTML标记名称之类的计算问题时，您希望使用不变式。

In most cases when dealing with user data, you actually want to use CurrentCultureIgnoreCase (or the ContainsAnyCase extension method), because that way you let the system handle upper/lowercase issues, which depend on the language. When dealing with computational issues, like names of HTML tags and so on, you want to use the invariant culture.

例如：在土耳其语中，大写字母<$ c小写的$ c> I 是ı （不带点），而不是 i （带点）。

For example: In Turkish, the uppercase letter I in lowercase is ı (without a dot), and not i (with a dot).

这篇关于如何在C＃中检查字符串是否包含字符？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！