To better understand how to use regular expressions in a C # environment, I write some regular expressions that might be useful to you, and these expressions are used in other contexts, hoping to help you.
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);
Swap the 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$1", 1);
Key word = value
string t3 = "Myval = 3";
String P3 = @ "(\w+) \s*=\s* (. *) \s*$";
Match m3 = regex.match (t3, p3);
Implement 80 characters per line
string t4 = "********************"
+ "******************************"
+ "******************************";
string P4 = ". {80,} ";
Match M4 = Regex.match (T4, p4);
Month/day/year hours: minutes: Seconds of time format
String T5 = "01/01/01 16:10:01";
string P5 = @ "(\d+)/(\d+)/(\d+) (\d+):(\d+):(\d+)";
Match M5 = Regex.match (T5, p5);
Change directory (Windows platform only)
string T6 = @ "C:\Documents and settings\user1\desktop\";
string r6 = Regex.Replace (t6,@ "\\user1\\", @ "\\user2\\");
Extended 16-bit escape characters
String t7 = "%41"; Capital A
String P7 = "% ([0-9a-fa-f][0-9a-fa-f])";
String R7 = Regex.Replace (T7, P7, Hexconvert);
Delete comments in C language (to be perfected)
string T8 = @ "
/*
* Traditional style annotation
*/
";
String P8 = @ "
/\* # matches the delimiter at the beginning of the comment
.*? # matching annotations
\*/# matching Comment End delimiter
";
String r8 = Regex.Replace (T8, P8, "", "XS");
Deletes a space at the beginning and end of a string
String t9a = "leading";
String p9a = @ "^\s+";
String r9a = Regex.Replace (t9a, p9a, "");
String t9b = "trailing";
String p9b = @ "\s+$";
String r9b = Regex.Replace (t9b, p9b, "");
Add the character n after the character \ to make it a true new line
string T10 = @ "\ntest\n";
string R10 = Regex.Replace (T10, @ "\\n", "\ n");
Convert IP Address
String T11 = "55.54.53.52";
String p11 = "^" +
@ "([01]?\d\d|2[0-4]\d|25[0-5]) \." +
@ "([01]?\d\d|2[0-4]\d|25[0-5]) \." +
@ "([01]?\d\d|2[0-4]\d|25[0-5]) \." +
@ "([01]?\d\d|2[0-4]\d|25[0-5])" +
"$";
Match M11 = Regex.match (T11, p11);
Delete the path that the file name contains
String T12 = @ "C:\file.txt";
String p12 = @ "^.*\\";
String R12 = Regex.Replace (T12, P12, "");
Join rows in multiple-line strings
string t13 = @ "This is
A split line ";
string p13 = @ "\s*\r?\n\s*";
String R13 = Regex.Replace (t13, P13, "");
Extracts all numbers in a string
string t14 = @ "
Test 1
Test 2.3
Test 47
";
String p14 = @ "(\d+\.? \d*|\.\d+) ";
MatchCollection mc14 = regex.matches (t14, p14);
Find all the Caps
String t15 = "This is a Test of all Caps";
String p15 = @ "(\b[^\wa-z0-9_]+\b)";
MatchCollection mc15 = regex.matches (t15, P15);
Find a lowercase word
String t16 = "This is A Test of lowercase";
string p16 = @ "(\b[^\wa-z0-9_]+\b)";
MatchCollection MC16 = regex.matches (t16, p16);
Find the word with the first letter as uppercase
String t17 = "This is A Test of Initial Caps";
String p17 = @ "(\b[^\wa-z0-9_][^\wa-z0-9_]*\b)";
MatchCollection MC17 = regex.matches (t17, p17);
Find a link in a simple HTML language
String t18 = @ "
<a href= "" first.htm "" >first tag text</a>
<a href= "" next.htm "" >next tag text</a>
";
string p18 = @ "<a[^>]*?" Href\s*=\s*[""]? "+ @" ([^ ' "" >]+?) ["]?>";
MatchCollection mc18 = regex.matches (t18, p18, "Si");
