过滤字符串 [英] Filtering a string

问题描述

我有一些字符串，我想使用过滤器查看它们是否包含某些字符.

I have some strings and I am wanting to see if they contain certain characters by using a filter.

以下是我正在谈论的那种事情的一个例子......

The following is an example of the kind of thing that I am talking about...

Dim files() As String = IO.Directory.GetFiles("folder path", filter)

除了基于过滤器获取文件之外，我想通过过滤器检查字符串.过滤器可以包含通配符、必需字符等的地方

Except, rather than getting files based on a filter, I am wanting to check a string via a filter. Where the filter can contain wildcards, required characters etc etc

希望这是有道理的...

Hopefully that makes sense...

推荐答案

除了正则表达式之外，VB.NET 还提供了另一种 - 易于使用的方式:

Apart from RegularExpressions, VB.NET provides another - easy-to-use way:

Like-Operator

Characters in pattern        Matches in string
          ?                  Any single character
          *                  Zero or more characters
          #                  Any single digit (0–9)
    [ charlist ]             Any single character in charlist
    [! charlist ]            Any single character not in charlist

如何:将字符串与模式匹配 (Visual Basic)

来自 MSDN 的一些示例

Some examples from MSDN

检查一个七位数的电话号码 phoneNum 是否正好有三个数字，后跟一个空格、一个连字符 (-)、一个句点 (.)，或者根本没有字符，后跟四个数字:

Check for a seven-digit telephone number phoneNum for exactly three numeric digits, followed by a space, a hyphen (–), a period (.), or no character at all, followed by exactly four numeric digits:

Dim sMatch As Boolean = 
  (phoneNum Like "###[ -.]####") OrElse (phoneNum Like "#######")

其他模式:

Dim testCheck As Boolean
' The following statement returns True (does "F" satisfy "F"?)
testCheck = "F" Like "F"
' The following statement returns False for Option Compare Binary
'    and True for Option Compare Text (does "F" satisfy "f"?)
testCheck = "F" Like "f"
' The following statement returns False (does "F" satisfy "FFF"?)
testCheck = "F" Like "FFF"
' The following statement returns True (does "aBBBa" have an "a" at the
'    beginning, an "a" at the end, and any number of characters in 
'    between?)
testCheck = "aBBBa" Like "a*a"
' The following statement returns True (does "F" occur in the set of
'    characters from "A" through "Z"?)
testCheck = "F" Like "[A-Z]"
' The following statement returns False (does "F" NOT occur in the 
'    set of characters from "A" through "Z"?)
testCheck = "F" Like "[!A-Z]"
' The following statement returns True (does "a2a" begin and end with
'    an "a" and have any single-digit number in between?)
testCheck = "a2a" Like "a#a"
' The following statement returns True (does "aM5b" begin with an "a",
'    followed by any character from the set "L" through "P", followed
'    by any single-digit number, and end with any character NOT in
'    the character set "c" through "e"?)
testCheck = "aM5b" Like "a[L-P]#[!c-e]"
' The following statement returns True (does "BAT123khg" begin with a
'    "B", followed by any single character, followed by a "T", and end
'    with zero or more characters of any type?)
testCheck = "BAT123khg" Like "B?T*"
' The following statement returns False (does "CAT123khg"?) begin with
'    a "B", followed by any single character, followed by a "T", and
'    end with zero or more characters of any type?)
testCheck = "CAT123khg" Like "B?T*"

我很确定引擎盖下的 LIKE-Operator 也是 作为RegularExpression 的一个子集实现，但它更容易用于简单的需求.

I'm pretty sure that the LIKE-Operator under the hood is also implemented as a subset of RegularExpression, but it's easier to use for simple requirements.

以下是 LIKE-Operator 和 RegularExpressions 之间的区别列表:

Here is a list of differences between LIKE-Operator and RegularExpressions:

正则表达式与 Like 运算符 (Visual Basic)

我喜欢它;-)

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