The difference between php-pcre and POSIX regular expressions

POSIX Regular expression extensions have been deprecated since PHP 5.3.0. There are some differences between POSIX regular and PCRE, and this article lists the most significant differences that need to be known when steering PCRE.

The PCRE function requires that the pattern be closed with a delimiter.

Unlike the posix,pcre extension, there is no specific function for case-insensitive matching. Instead, support for the same work is done using the I (pcre_caseless) pattern modifier. Other pattern modifiers can also be used to change the matching policy.

The POSIX function looks for the longest match from the left, but PCRE stops after the first legal match. If the string does not match this is no different, but if the match, both in the result and speed will be different. To illustrate this difference, consider the following example (from Jeffrey Friedl, "Mastering regular Expressions"). Use mode one (self)? (selfsufficient)? Match on the string oneselfsufficient, PCRE will match to oneself, but with POSIX, the result will be the entire string oneselfsufficient. Two substrings match the original string, but POSIX will have the longest result.

function Comparison Table

Posix

PCRE

Ereg_replace () preg_replace ()

Ereg () Preg_match ()

Eregi_replace () preg_replace ()

Eregi () Preg_match ()

Split () Preg_split ()

Spliti () Preg_split ()

Sql_regcase () No equivalent function

