There's a way to transform a data value into another defined in a regex pattern?
I mean, I want to define a pattern like a=1|b=2|c=3.
So when if I pass the a value to Regex it returns me 1. If b returns 2 ... etc.
It's that possible?
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Could you provide a sample source value?Sven Grosen– Sven Grosen2013-11-05 17:48:12 +00:00Commented Nov 5, 2013 at 17:48
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Why would you want to use a regex for this? It is not what they are made for.CompuChip– CompuChip2013-11-05 17:49:31 +00:00Commented Nov 5, 2013 at 17:49
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Why do you want to use regex for a simple replace scenario?Nickolai Nielsen– Nickolai Nielsen2013-11-05 17:59:58 +00:00Commented Nov 5, 2013 at 17:59
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1it's not even a replacement -- just KVPs.Reacher Gilt– Reacher Gilt2013-11-05 18:01:58 +00:00Commented Nov 5, 2013 at 18:01
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4 Answers
Dictionary<string, int> dic = new Dictionary<string, int>();
foreach (Match m in Regex.Matches("a=1|b=2|c=3", @"\w?=\d?"))
{
string[] val = m.Value.Split('=');
dic.Add(val[0], Int32.Parse(val[1]));
}
Or
string val = "a";
Int32.Parse(Regex.Match("a=1|b=2|c=3", val + @"=(\d)").Groups[1].Value);
3 Comments
Reacher Gilt
@Maximus-Decimus Because the sample input you've provided is delimited key value pairs, this is a very strong solution. I don't think there's a need for you to do your work with Regexes given how simple and well formatted your input is.
You can do this in C# like this:
var input = "a, b, c";
Dictionary<string, string> lookup = new Dictionary<string, string>()
{
{"a", "1"},
{"b", "2"},
{"c", "3"}
};
string result = Regex.Replace(input, "[abc]", m => lookup[m.Value] , RegexOptions.None);
Console.WriteLine(result); // outputs 1, 2, 3
I have used the regular expression [abc] which matches either a, b or c then depending on the match, the delegate used inside Replace() looks the match inside a dictionary to decide what to replace it with.
3 Comments
Ibrahim Najjar
@sln Then you would use the alternation. It seems that the OP didn't even want this which surprises me, but it doesn't matter now because the problem was solved. Thank you.
You could use Regex.Replace with a delegate to evaluate the matches.
See: http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.matchevaluator(v=vs.110).aspx and: http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex.replace(v=vs.110).aspx
1 Comment
Alexei Levenkov
+0: almost nice answer - adding sample code that applies to OP case would make it much better.
The answer is NO. Regex only return match sucess/fail and that which matches the pattern.
You could however determine a group number match, and that may enable you to translate
that into a value or whatever you want.
But be sure the power of regex is really needed for the job, and not just a simple string compare.
Otherwise you could build a custom trie.
Pseudo code:
pattern = @"
( Enie ) # (1)
| ( Menie ) # (2)
| ( Minie ) # (3)
| ( Moe ) # (4)
";
int GetValue( string& str )
{
smatch match;
if ( regex_find ( pattern, str, match, flags.expanded ) )
{
if ( match[1].matched )
return val1;
if ( match[2].matched )
return val2;
if ( match[3].matched )
return val3;
if ( match[4].matched )
return val4;
}
}