如何阅读在C#中的正则表达式捕获 [英] How to read RegEx Captures in C#
问题描述
我开始一个C#的书,我决定正则表达式的扔到组合,使枯燥的练习控制台稍微更有趣。我想要做的就是索要他们的电话号码,用户在控制台中,检查对正则表达式,然后捕获的数字,所以我可以格式化他们,我想要的方式。我已经得到了所有的工作,除了正则表达式捕获的一部分。如何获取捕捉值到C#的变量?
也随时纠正任何code格式或变量命名的问题。
静态无效askPhoneNumber()
{
字符串模式= @[(](\\ d {3})?[)] [ - ](\\ D {3}) - (\\ d {4})?[]?; 的System.Console.WriteLine(什么是你的电话号码吗?);
字符串phoneNumber的=到Console.ReadLine(); 而(!Regex.IsMatch(phoneNumber的,图案))
{
Console.WriteLine(坏输入);
phoneNumber的=到Console.ReadLine();
} 匹配匹配= Regex.Match(phoneNumber的,图案);
捕捉捕捉= match.Groups.Captures; 的System.Console.WriteLine(捕捉[1] .value的+ - +捕捉[2] .value的+ - +捕捉[3]。价值);
}
C#的正则表达式API可能会相当混乱。还有的集团的和的捕获的:
- A 组的再presents捕获组,它被用来从文本 抽取子
- 可以有多个的捕获的每个组,如果组一个量词内出现。
的层次是:
- 匹配
- 集团
- 捕获
- 集团
(匹配可以有多个组,每个组可以有几个捕获)
例如:
主题:aabcabbc
图案:^ C)+ $(:( A + B +?)
在这个例子中,只有一个组:(A + B +)
。这组是一个量词内,并匹配两次。它生成两个的捕获的 AAB
和羊毛
:
aabcabbc
^^^ ^^^
CAP1 CAP2
在一组不是一个数量里面,它会产生只有一个捕获。你的情况,你有3组,每组拍摄一次。您可以使用 match.Groups [1] .value的
, match.Groups [2] .value的
和 match.Groups [3] .value的
来提取3子你有兴趣,而不诉诸的捕获的概念都没有。
I started a C# book and I decided to throw RegEx's into the mix to make the boring console exercises a little more interesting. What I want to do is ask a user for their phone number in the console, check it against a RegEx, then capture the digits so I can format them the way I want. I've got all that working except the RegEx capture part. How do I get the capture values into C# variables?
Also feel free to correct any code formatting or variable naming issues.
static void askPhoneNumber()
{
String pattern = @"[(]?(\d{3})[)]?[ -.]?(\d{3})[ -.]?(\d{4})";
System.Console.WriteLine("What is your phone number?");
String phoneNumber = Console.ReadLine();
while (!Regex.IsMatch(phoneNumber, pattern))
{
Console.WriteLine("Bad Input");
phoneNumber = Console.ReadLine();
}
Match match = Regex.Match(phoneNumber, pattern);
Capture capture = match.Groups.Captures;
System.Console.WriteLine(capture[1].Value + "-" + capture[2].Value + "-" + capture[3].Value);
}
The C# regex API can be quite confusing. There are groups and captures:
- A group represents a capturing group, it's used to extract a substring from the text
- There can be several captures per group, if the group appears inside a quantifier.
The hierarchy is:
- Match
- Group
- Capture
- Group
(a match can have several groups, and each group can have several captures)
For example:
Subject: aabcabbc
Pattern: ^(?:(a+b+)c)+$
In this example, there is only one group: (a+b+)
. This group is inside a quantifier, and is matched twice. It generates two captures: aab
and abb
:
aabcabbc
^^^ ^^^
Cap1 Cap2
When a group is not inside of a quantifier, it generates only one capture. In your case, you have 3 groups, and each group captures once. You can use match.Groups[1].Value
, match.Groups[2].Value
and match.Groups[3].Value
to extract the 3 substrings you're interested in, without resorting to the capture notion at all.
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