Regular Expression 使用规则

        1、正则表达式通常被用来检索、替换那些符合某个模式(规则)的文本。

        2、给定一个正则表达式和另一个字符串,可以达到如下目的：

                          （1）给定的字符串是否符合正则表达式的过滤逻辑（称作“匹配”）；

                          （2）可以通过正则表达式，从字符串中获取我们想要的特定部分。

        3、正则表达式"testing"中没有包含任何元字符，它可以匹配"testing"和"testing123"等字符串，但是不能匹配"Testing"。

        4、正则表达式是区分大小写的，如果要忽略大小写可使用方括号表达式“[]”。只要匹配的字符出现在方括号内，即可表示匹配成功。但要注意：一个方括号只能匹配一个字符。例如，要匹配的字串tm不区分大小写，那么该表达式应该写作如下格式：[Tt][Mm].

用正则表达式写出查找姓名，电话，邮件的表达式
name:       var str = "My name is Linda";
                 var n = str.search(/Linda/i);

phone:      var str= "My phone is 15152180476";
                 var n =str .search(/15152180476/i); 

email:        var str= "My email is [email protected]";
                 var n =str .search(/[email protected]/i); 

引用自https://www.cnblogs.com/l69-l54/p/9846595.html

• Download Installation File - 88 Kb
• Download Source Code - 91 Kb

Introduction

The .NET framework provides a powerful class Regex for creating and using Regular Expressions. While regular expressions are a powerful way to parse, edit, and replace text, the complex syntax makes them hard to understand and prone to errors, even for the experienced user. When developing code that uses regular expressions, I have found it very helpful to create and debug my expressions in a separate tool to avoid time consuming compile/debug cycles. Expresso enables me to do the following:

• Build complex regular expressions by selecting components from a palette

• Test expressions against real or sample input data

• Display all matches in a tree structure showing captured groups, and all captures within a group

• Build replacement strings and test the match and replace functionality

• Highlight matched text in the input data

• Automatically test for syntax errors

• Generate Visual Basic or C# code that can be incorporated directly into programs

• Read or save regular expressions and input data

Background

Regular expressions are a sophisticated generalization of the "wildcard" syntax that users of Unix, MSDOS, Perl, AWK, and other systems are already familiar with. For example, in MSDOS, one can say:

 Collapse

dir *.exe

to list all of the files with the exe extension. Here the asterisk is a wildcard that matches any character string and the period is a literal that matches only a period. For decades, much more complex systems have been used to great advantage whenever it is necessary to search text for complex patterns in order to extract or edit parts of that text. The .NET framework provides a class called Regex that can be used to do search and replace operations using regular expressions. In .NET, for example, suppose we want to find all the words in a text string. The expression \wwill match any alphanumeric character (and also the underscore). The asterisk character can be appended to \w to match an arbitrary number of repetitions of \w, thus \w* matches all words of arbitrary length that include only alphanumeric characters (and underscores).

Expresso provides a toolbox with which one can build regular expressions using a set of tab pages from which any of the syntactical elements can be selected. After building an expression, sample data can be read or entered manually, and the regular expression can be run against that data. The results of the search are then displayed, showing the hierarchy of named groups that Regex supports. The tool also allows testing of replacement strings and generation of code to be inserted directly into a C# or Visual Basic .NET program.

The purpose of this article is not to give a tutorial on the use of regular expressions, but rather to provide a tool for both experienced and novice users of regular expressions. Much of the complex behavior of regular expressions can be learned by experimenting with Expresso.

The reader may also find it helpful to explore some of the code within Expresso to see examples of the use of regular expressions and the Regexclass.

Using Expresso to Build and Test Regular Expressions on Sample Input Data

To use Expresso, download and run the executable file, which requires the .NET Framework. If you want to explore the code, download and extract the source files, open the solution within Visual Studio .NET, then compile and run the program. Expresso will start with sample data preloaded into the "Input Data" box (refer to the figure above). Create your own regular expression or select one of the examples from the list box. Click "Find Matches" to test the regular expression. The matches are shown in a tree structure in the "Results" box. Multiple groups and captures can be displayed by expanding the plus sign as shown above.

To begin experimenting with your own regular expressions, click the "Show Builder" button. It will display a set of tab pages as shown here:

In this example, the expression \P{IsGreek}{4,7}? has been generated by setting options that specify: match strings of four to seven characters, but with as few repetitions as possible, of any characters other than Greek letters. By clicking the "Insert" button, this expression will be inserted into the regular expression that is being constructed in the text box that contains the regular expression that will be used by the "FindMatch" or "Replace" buttons. Using the other tab pages, all of the syntactical elements of .NET regular expressions can be tested.

The Regex class supports a number of options such as ignoring the case of characters. These options can be specified using check boxes on the main form of the application.

Replacement strings may be built using the various expressions found on the "Substitutions" tab. To test a replacement pattern, enter a regular expression, a replacement string, some input data, and then click the "Replace" button. The output will be shown in the "Results" box.

Using Expresso to Generate Code

Once a regular expression has been thoroughly debugged, code can be generated by selecting the appropriate option in the "Code" menu. For example, to generate code for a regular expression to find dates, create the following regular expression (or select this example from the drop down list):

 Collapse

(?<Month>\d{1,2})/(?<Day>\d{1,2})/(?<Year>(?:\d{4}|\d{2}))

By selecting the "Make C# Code" from the "Code" menu, the following code is generated. It can be saved to a file or cut and pasted into a C# program to create a Regex object that encapsulates this particular regular expression. Note that the regular expression itself and all the selected options are built into the constructor for the new object:

 Collapse

using System.Text.RegularExpressions;

Regex regex = new Regex(
    @"(?<Month>\d{1,2})/(?<Day>\d{1,2})/(?<Yea"
    + @"r>(?:\d{4}|\d{2}))",
    RegexOptions.IgnoreCase
    | RegexOptions.Multiline
    | RegexOptions.IgnorePatternWhitespace
    | RegexOptions.Compiled
    );

Points of Interest

After creating this tool, I discovered the Regex Workbench by Eric Gunnerson, which was designed for the same purpose. Expresso provides more help in building expressions and gives a more readable display of matches (in my humble opinion), but Eric''s tool has a nice feature that shows Tooltips that decode the meaning of subexpressions within an expression. If you are serious about regular expressions, try both of these tools!

History

Original Version: 2/17/03

Version 1.0.1148: 2/22/03 - Added a few additional features including the ability to create an assembly file and registration of a new file type (*.xso) to support Expresso Project Files.

Version 1.0.1149: 2/23/03 - Added a toolbar.

My brother John doesn''t like the name Expresso, since he says too many people are already confused about the proper spelling and pronunciation of Espresso. Somehow, I doubt this program will have any impact on the declining literacy of America, but who knows. John prefers my earlier name "Mr. Mxyzptlk", after the Superman character with the unpronounceable name.

For the latest information on Expresso (if any), see http://www.ultrapico.com/ .

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

//NSString+RegEx.h
#import <Foundation/Foundation.h>
@interface NSString (RegEx)
#pragma mark - NSPredicate
- (BOOL)mars_matchedByPrdicateToRegEx:(NSString *)regEx;
@end
//NSString+RegEx.m
#import "NSString+RegEx.h"
@implementation NSString (RegEx)
#pragma mark - NSPredicate
- (BOOL)mars_matchedByPrdicateToRegEx:(NSString *)regEx{
  NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regEx];
  return [predicate evaluateWithObject:self];
}

@end

//NSString+RegEx.h
#import <Foundation/Foundation.h>

@interface NSString (RegEx)

#pragma mark - NSRegularExpression

//校验是否匹配
- (BOOL)mars_matchedToRegEx:(NSString *)regEx;

//匹配到的第一个字符串
- (NSString *)mars_firstMatchToRegEx:(NSString *)regEx;

//所有匹配的字符串
- (NSArray *)mars_matchesToRegEx:(NSString *)regEx;

//替换匹配到的字符串
- (NSString *)mars_stringByReplaceMatchesToRegEx:(NSString *)regEx replaceString:(NSString *)replaceString;

@end

//NSString+RegEx.m
#import "NSString+RegEx.h"

@implementation NSString (RegEx)

#pragma mark - NSRegualrExpression

//校验是否匹配
- (BOOL)mars_matchedToRegEx:(NSString *)regEx{
  
  NSError *error;
  NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];
  
  NSUInteger number = [regularExpression numberOfMatchesInString:self options:0 range:NSMakeRange(0, self.length)];
  return number != 0;
}

//匹配到的第一个字符串
- (NSString *)mars_firstMatchToRegEx:(NSString *)regEx{
  NSError *error;
  NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];
  NSTextCheckingResult *firstMatch = [regularExpression firstMatchInString:self options:0 range:NSMakeRange(0, self.length)];
  if (firstMatch) {
    NSString *result = [self substringWithRange:firstMatch.range];
    return result;
  }
  return nil;
}

//所有匹配的字符串
- (NSArray *)mars_matchesToRegEx:(NSString *)regEx{
  NSError *error;
  NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];
  
  NSArray *matchArray = [regularExpression matchesInString:self options:0 range:NSMakeRange(0, self.length)];
  
  NSMutableArray *array = [NSMutableArray array];
  if (matchArray.count != 0) {
    for (NSTextCheckingResult *match in matchArray) {
      NSString *result = [self substringWithRange:match.range];
      [array addObject:result];
    }
  }
  
  return array;
}

//替换匹配到的字符串
- (NSString *)mars_stringByReplaceMatchesToRegEx:(NSString *)regEx replaceString:(NSString *)replaceString{
  NSError *error;
  NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];

  return [regularExpression stringByReplacingMatchesInString:self options:0 range:NSMakeRange(0, self.length) withTemplate:replaceString];
}

@end

• Java Predicate及Consumer接口函数代码实现解析
• SpringCloud Gateway加载断言predicates与过滤器filters的源码分析
• C#中的Action、Func和Predicate如何使用
• iOS中谓词（NSPredicate）的基本入门使用教程
• iOS中NSPredicate谓词的使用
• 30分钟快速带你理解iOS中的谓词NSPredicate
• 与Func泛型委托的用法实例" target="_blank">C#中Predicate<T>与Func<T, bool>泛型委托的用法实例
• 浅谈Java8新特性Predicate接口