21. Basic syntax for regular expressions

In the Pcre library function, the regular match pattern consists of delimiters and metacharacters, which can be any character that is non-numeric, non-backslash, and not a space. Frequently used delimiters are forward slashes (/), hash symbols (#), and inverse symbols (~), for example:

/foo bar/#^[^0-9]$#~php~

If the pattern contains delimiters, the delimiter needs to be escaped with a backslash (\).

/http:\/\//

If the pattern contains more split characters, it is recommended that you replace other characters as separators, or you can escape them with preg_quote.

$p = ' http:/'; $p = '/'. Preg_quote ($p, '/'). ' /'; echo $p;

The pattern modifier can be used after the delimiter, including: I, M, S, X, and so on, such as using the I modifier to ignore case matching:

$str = "Http://www.imooc.com/", if (Preg_match ('/http/i ', $str)) {    echo ' matches successfully ';}

21. Basic syntax for regular expressions