using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(?<=last_name\\\"":\\\"")(\w)+(?=\\)";
string input = @"{""message"":""{\""_\"":\""user\"",\""pFlags\"":{\""contact\"":true},\""user_flags\"":2143,\""id\"":702212125,\""access_hash\"":\""914250561826\"",\""first_name\"":\""david\"",\""last_name\"":\""jones\"",\""username\"":\""david_d192\"",\""phone\"":\""051863329875\"",\""status\"":{\""_\"":\""userStatusRecently\""}}"",""phone"":""051863329875"",""version"":""3"",""type"":""unknown"",""token"":""1556189892619764206"",""p_id"":702212125,""username"":""david_d192"",""type"":""redis"",""user_flags"":2143,""host"":""win"",from"":""contacts""}
{""index"": {""_type"": ""_doc"", ""_id"": ""36GG54F""}}
{""message"":""{\""_\"":\""user\"",\""pFlags\"":{\""contact\"":true},\""user_flags\"":2143,\""id\"":702212125,\""access_hash\"":\""914250561826\"",\""first_name\"":\""david\"",\""last_name\"":\""jones\"",\""username\"":\""david_d192\"",\""phone\"":\""051863329875\"",\""status\"":{\""_\"":\""userStatusRecently\""}}"",""phone"":""051863329875"",""version"":""3"",""type"":""unknown"",""token"":""1556189892619764206"",""p_id"":702212125,""username"":""david_d192"",""type"":""redis"",""user_flags"":2143,""host"":""win"",from"":""contacts""}
{""index"": {""_type"": ""_doc"", ""_id"": ""36GG54F""}}
{""message"":""{\""_\"":\""user\"",\""pFlags\"":{\""contact\"":true},\""user_flags\"":2143,\""id\"":702212125,\""access_hash\"":\""914250561826\"",\""first_name\"":\""david\"",\""last_name\"":\""jones\"",\""phone\"":\""051863329875\"",\""status\"":{\""_\"":\""userStatusRecently\""}}"",""phone"":""051863329875"",""version"":""3"",""type"":""unknown"",""token"":""1556189892619764206"",""p_id"":702212125,""type"":""redis"",""user_flags"":2143,""host"":""win"",from"":""contacts""}
{""index"": {""_type"": ""_doc"", ""_id"": ""36GG54F""}}
#Target: id, first_name , last_name , phone , username(if exist)";
RegexOptions options = RegexOptions.Multiline;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx