preg_last_error

Name:preg_last_error

Category:Regular processing PCRE

Programming Language:php

One-line Description:Returns an error code indicating the reason for the recent regex call to fail.

Definition and usage

preg_last_error() function returns the error code for the recently evaluated regular expression. The returned value will match one of the following constants:

constant	describe
PREG_NO_ERROR	No error occurred.
PREG_INTERNAL_ERROR	An error occurred while evaluating the expression.
PREG_BACKTRACK_LIMIT_ERROR	The number of backtraces required to evaluate an expression exceeds the limit given in the PHP configuration.
PREG_RECURSION_LIMIT_ERROR	The recursion depth required to evaluate an expression exceeds the limits given in the PHP configuration.
PREG_BAD_UTF8_ERROR	The input string contains invalid UTF-8 data.
PREG_BAD_UTF8_OFFSET_ERROR	During evaluation, the string offset does not point to the first character of the multibyte UTF-8 symbol.
PREG_JIT_STACKLIMIT_ERROR	The JIT compiler exhausts stack memory while trying to evaluate expressions.

Example

Use preg_last_error() to handle errors:

 <?php
$str = 'This regular expression is invalid. ' ;
$pattern = '/invalid//' ;
$match = @ preg_match ( $pattern , $str , $matches ) ;

if ( $match === false ) {
  // An error occurred
  $err = preg_last_error ( ) ;
  if ( $err == PREG_INTERNAL_ERROR ) {
    echo 'regex is invalid. ' ;
  }
} else if ( $match ) {
  // Find a match
  echo $matches [ 0 ] ;
} else {
  // No match found
  echo 'No match found' ;
}
?>