Snippet for http://kobikobi.wordpress.com/2011/04/25/net-regular-expressions-using-the-stack-state-to-understand-numeric-values/ - capture a decimal number followed by the same number in binary base using nothing but regex and time.
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using System; | |
using System.Collections.Generic; | |
using System.Text.RegularExpressions; | |
namespace ConsoleApplication1 | |
{ | |
// sample for http://kobikobi.wordpress.com/2011/04/25/net-regular-expressions-using-the-stack-state-to-understand-numeric-values/ | |
class Program | |
{ | |
static void Main(string[] args) | |
{ | |
string sampleText = "10:1010 3:11 4:100 4:101 5:101 1:1 1342:10100111110 1342:10100111111 1342:10100111101 0:0"; | |
MatchCollection pairs = Regex.Matches(sampleText, DecimalNumberAndEqualBinaryNumber, | |
RegexOptions.IgnorePatternWhitespace | RegexOptions.Compiled); | |
foreach (Match match in pairs) | |
{ | |
Console.WriteLine(match.Value); | |
} | |
Console.ReadKey(); | |
} | |
public static readonly string DecimalNumberAndEqualBinaryNumber = @" | |
\b | |
(?> | |
(?=[0-9]) | |
# multiply the content of the stack by 10 | |
(?(Decimal) | |
(?<-Decimal> | |
(?<Temp>){10} | |
) | |
){100000} | |
(?(Decimal)(?!)) | |
(?(Temp) | |
(?<-Temp> | |
(?<Decimal>) | |
) | |
){100000} | |
(?(Temp)(?!)) | |
# match a digit, and push its value to the stack | |
(?: | |
0 | | |
1 (?<Decimal>) | | |
2 (?<Decimal>){2} | | |
3 (?<Decimal>){3} | | |
4 (?<Decimal>){4} | | |
5 (?<Decimal>){5} | | |
6 (?<Decimal>){6} | | |
7 (?<Decimal>){7} | | |
8 (?<Decimal>){8} | | |
9 (?<Decimal>){9} | |
) | |
)+ | |
: | |
(?> | |
(?=[01]) | |
# multiply the content of the stack by 2 | |
(?(Binary) | |
(?<-Binary> | |
(?<Temp>){2} | |
) | |
){100000} | |
(?(Binary)(?!)) | |
(?(Temp) | |
(?<-Temp> | |
(?<Binary>) | |
) | |
){100000} | |
(?(Temp)(?!)) | |
# match a digit, and push its value to the stack | |
(?: | |
0 | | |
1 (?<Binary>) | |
) | |
)+ | |
\b | |
# Check both stacks are the same length | |
(?(Decimal) | |
(?<-Decimal>) | |
(?<-Binary>) | |
){100000} | |
(?(Decimal)(?!)) | |
(?(Binary)(?!)) | |
"; | |
} | |
} |
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