Regular expression for php knowledge point review

In the previous article, why? {N} {m, n} {n.} refers to the http://www.2cto.com/kf/201202/118458.html...

// Technical knowledge of regular expressions
 
 
// [] Define character set and example [a-z] [A-Z] [0-9] [\ f \ r \ n \ t]
 
 
// Positioning character ^ [A-Z] [0-9] $ beginning and end
 
 
// Quantifiers * +? {N} {m, n} {n.} indicates the number of duplicates.
 
 
// Select |
 
 
// Printable character: the 33-127 character in ASCII, which is the space, deletion, carriage return, and cancellation characters that we can see.
 
 
// POSOX regular expression
// Common functions
Echo"
";
$ B4 = "abc ";
$ Pattern = "[[: alpha:]";
Echo ereg ($ pattern, $ b4 );
// Output 1
// Eregi () unsigned
 
 
 
 
 
$ B7 = "asd & ass @ ass & adfdf ";
 
$ Pattern1 = "&";
$ Pattern2 = "[& @]";
Print_r (split ($ pattern1, $ b7 ));
Print_r (split ($ pattern2, $ b7 ));
 
 
Echo"
";
$ B8 = "helloworld ";
$ Pattern3 = "world ";
$ Replacement1 = "persion ";
Echo ereg_replace ($ pattern3, $ replacement1, $ b8 );
 
 
Echo"
";
Echo SQL _regcase ("abcdefg ");
// Output: [Aa] [Bb] [Cc] [Dd] [Ee] [Ff] [Gg]
 
 
// Perl regular expression perl is an extra extended \ d number \ D non-digit \ s blank \ S non-blank \ w letter mathematical symbol underline \ W non-letter number on the basis of posix underline
 
// Common functions: array preg_grep (string pattern, array input)
Echo"
";
$ W1 = array ("adad", "adad4", "asda", "1asf3", "sdfs ");
$ Fl_array = preg_grep ("/^ \ D {1, }$/", $ w1); // emphasize {1 here,} instead of {1.} in posix .}
Print_r ($ fl_array );
 
 
Echo"
";
Echo preg_match ("/a/", "abc ");
// Output 1
 
 
Echo"
";
// \ B indicates the word boundary
If (preg_match ("/\ bweb \ B/I", "PHP is the web scripting language of choice .")){
Print "A match was found .";
} Else {
Print "A match was not found .";
}
 
 
If (preg_match ("/\ bweb \ B/I", "PHP is the website scripting language of choice .")){
Print "A match was found .";
} Else {
Print "A match was not found .";
}
// Especially when matching email addresses
 
 
Echo"
";
$ Pattern5 = "/[\ *] + /";
$ W3 = "aaa *** bbb * ccc ";
Print_r (preg_split ($ pattern5, $ w3 ));
 
 
Echo"
";
$ Pattern6 = "/world /";
$ Content2 = "girl ";
$ Tre = "hello world ";
Echo preg_replace ($ pattern6, $ content2, $ tre );
 
 
// String preg_quote (string str [, string delimiter]) escape
Echo"
";
$ Keywords = "$40 for a g3/400 ";
$ Keywords = preg_quote ($ keywords, "/"); // if this field is not added, it will not escape/in g3/400 /;
Echo $ keywords;
 
From the column kaituozhe345