格式化电话号码[重复]答案

【问题标题】：Formatting a Phone number [duplicate]格式化电话号码[重复]
【发布时间】：2014-05-08 15:07:38
【问题描述】：

如何将电话号码从 (###)###-#### 格式化为 ##########？有没有最好的方法来做到这一点？我可以使用String.Substring 来获取每个数字块，然后将它们连接起来。但是，还有其他复杂的方法吗？

【问题讨论】：

【解决方案1】：

简单的正则表达式替换怎么样？

string formatted = Regex.Replace(phoneNumberString, "[^0-9]", "");

这实际上只是一个数字白名单。看到这个小提琴：http://dotnetfiddle.net/ssdWSd

输入：(123) 456-7890

输出：1234567890

【讨论】：

+ 是不必要的，因为该函数将查找所有满足指定正则表达式的子字符串并替换它。
@wei2912 你是对的，固定的。

【解决方案2】：

我会使用 LINQ：

var result = new String(phoneString.Where(x => Char.IsDigit(x)).ToArray());

虽然正则表达式也有效，但这不需要任何特殊设置。

【讨论】：

【解决方案3】：

一个简单的方法是：

myString = myString.Replace("(", "");
myString = myString.Replace(")", "");
myString = myString.Replace("-", "");

用空字符串替换每个字符。

【讨论】：

这行不通，因为它假定字符串是可变的，而事实并非如此。
我总是忘记这一点。我的编辑有效吗？
现在可以了。 -1 不是我写的。
这很酷。早点错了，估计是谁都回不来了。我不敢相信我多久忘记字符串在 c# 中是不可变的。有时我需要 15 分钟的调试时间才能发现它。

【解决方案4】：

试试这个：

resultString = Regex.Replace(subjectString, @"^\((\d+)\)(\d+)-(\d+)$", "$1$2$3");

正则表达式解释

^\((\d+)\)(\d+)-(\d+)$

Assert position at the beginning of the string «^»
Match the character “(” literally «\(»
Match the regex below and capture its match into backreference number 1 «(\d+)»
   Match a single character that is a “digit” (0–9 in any Unicode script) «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the character “)” literally «\)»
Match the regex below and capture its match into backreference number 2 «(\d+)»
   Match a single character that is a “digit” (0–9 in any Unicode script) «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the character “-” literally «-»
Match the regex below and capture its match into backreference number 3 «(\d+)»
   Match a single character that is a “digit” (0–9 in any Unicode script) «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Assert position at the end of the string, or before the line break at the end of the string, if any (line feed) «$»

$1$2$3

Insert the text that was last matched by capturing group number 1 «$1»
Insert the text that was last matched by capturing group number 2 «$2»
Insert the text that was last matched by capturing group number 3 «$3»

【讨论】：

愿意解释否决票吗？