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Technical knowledge of regular expressions
[] Define character sets and example [A-z] [a-z] [0-9] [\f\r\n\t]
Locator ^[a-z][0-9]$ Start end
Quantifier * +? {n} {m,n} {N.} Refers to the number of repetitions
Select |
Printable characters: 33-127 characters in ASCII, that is, we can see the symbol space, delete, enter, cancel and so on is typically non-printable characters
Posox Regular Expressions
Common functions
echo "
";
$b 4 = "abc";
$pattern = "[[: Alpha:]]";
Echo Ereg ($pattern, $b 4);
Output 1
Eregi () unsigned
$b 7 = "ASD&ASS@ASS&ADFDF";
$pattern 1 = "&";
$pattern 2 = "[&@]";
Print_r (Split ($pattern 1, $b 7));
Print_r (Split ($pattern 2, $b 7));
echo "
";
$b 8 = "HelloWorld";
$pattern 3 = "World";
$replacement 1 = "persion";
Echo ereg_replace ($pattern 3, $replacement 1, $b 8);
echo "
";
Echo sql_regcase ("ABCDEFG");
Output: [Aa][bb][cc][dd][ee][ff][gg]
Perl Regular Expression Perl is an additional extension on the basis of POSIX support \d digital \d non-numeric \s blank \s non-whitespace \w letter mathematical symbol underline \w non-alphanumeric sign underline
Common functions Array Preg_grep (string pattern, array input)
echo "
";
$w 1 = Array ("Adad", "Adad4", "Asda", "1asf3", "SDFs");
$FL _array = Preg_grep ("/^\d{1,}$/", $w 1);//The emphasis here is on {1,} instead of {1} in POSIX.
Print_r ($FL _array);
echo "
";
Echo Preg_match ("/a/", "abc");
Output 1
echo "
";
\b represents the boundary of a word
if (Preg_match ("/\bweb\b/i", "PHP is the Web scripting language of choice.")) {
Print "A match was found.";
} else {
Print "A match is 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 is not found.";
}
Especially when matching e-mail is commonly used
echo "
";
$pattern 5 = "/[\*]+/";
$w 3 = "AAA***BBB*CCC";
Print_r (Preg_split ($pattern 5, $w 3));
echo "
";
$pattern 6 = "/world/";
$content 2 = "Girl";
$tre = "Hello World";
Echo Preg_replace ($pattern 6, $content 2, $tre);
String Preg_quote (String str [, String delimiter]) escaped
echo "
";
$keywords = "g3/400 for a";
$keywords = Preg_quote ($keywords, "/");//If it is not added, it will not escape the g3/400;
Echo $keywords;
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