如何使用C＃从下面的字符串中提取键

Question

Input query

 select * from mytable where projectname = __$ProjectName$__ and  projectid = __$ProjectId$__ and env = __$EnvType$__

I want list of string ( List<string> ) as output below.(double underscore+dollar+"string"+dollar+double underscore) Language: C#

 __ $ProjectName$__
 __ $ProjectId$__
 __ $EnvType$__

Answer 1

使用Linq：

List<string> output = input.Split(' ').Where(x => x.StartsWith("__$") && x.EndsWith("$__")).ToList();

Answer 2

Try regular expressions ; if key

1. Starts from __$
2. Contains identifier (which starts from letter A..Z , a..z , can contain letters or\\and digits A..Z , a..z , 0..9 )
3. Ends with $__

the pattern to match is __\\$[A-Za-z]+[A-Za-z0-9]*\\$__

Code:

using System.Text.RegularExpressions;

...

string source = 
  "select * from mytable where projectname = __$ProjectName$__ and  projectid = __$ProjectId$__ and env = __$EnvType$__";

List<string> keys = Regex
  .Matches(source, @"__\$[A-Za-z]+[A-Za-z0-9]*\$__")
  .OfType<Match>()
  .Select(match => match.Value)
  .ToList();

Console.Write(string.Join(Environment.NewLine, keys));

Outcome:

__$ProjectName$__
__$ProjectId$__
__$EnvType$__

Answer 3

using System;
using System.Linq;
using System.Text.RegularExpressions;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var expression = @"select * from mytable where projectname = __$ProjectName$__ and  projectid = __$ProjectId$__ and env = __$EnvType$__";

            var output = new Regex(@"__\$[^\s]+?\$__")
                .Matches(expression)
                .Cast<Match>()
                .Select(m => m.Value)
                .ToList();

            output.ForEach(Console.WriteLine);
        }
    }
}