Cookbook Regular Expressions
To wrap up this overview of how regular expressions are used in C# applications, the following is a set of useful expressions that have been used in other environments.[3]
Matching roman numerals:
string p1 = "^m*(d?c{0,3}|c[dm])" + "(l?x{0,3}|x[lc])(v?i{0,3}|i[vx])$"; string t1 = "vii"; Match m1 = Regex.Match(t1, p1);
Swapping first two words:
string t2 = "the quick brown fox"; string p2 = @"(\S+)(\s+)(\S+)"; Regex x2 = new Regex(p2); string r2 = x2.Replace(t2, "$3$2$1", 1);
Matching “keyword = value” patterns:
string t3 = "myval = 3"; string p3 = @"(\w+)\s*=\s*(.*)\s*$"; Match m3 = Regex.Match(t3, p3);
Matching lines of at least 80 characters:
string t4 = "********************" + "******************************" + "******************************"; string p4 = ".{80,}"; Match m4 = Regex.Match(t4, p4);
Extracting date/time values (MM/DD/YY HH:MM:SS):
string t5 = "01/01/01 16:10:01"; string p5 = @"(\d+)/(\d+)/(\d+) (\d+):(\d+):(\d+)"; Match m5 = Regex.Match(t5, p5);
Changing directories (for Windows):
string t6 = @"C:\Documents and Settings\user1\Desktop\"; string r6 = Regex.Replace(t6, @"\\user1\\", @"\user2\");
Expanding (
%nn
) hex escapes:string t7 = "%41"; // capital A string p7 = "%([0-9A-Fa-f][0-9A-Fa-f])"; // uses a MatchEvaluator delegate string r7 = Regex.Replace(t7, p7, HexConvert);
Deleting C comments (imperfectly):
string t8 = @" /* * this is an old cstyle comment block */ "; string p8 = @" /\* # match the opening delimiter .*? # match a minimal numer ...
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