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Using Perl-style regular expressions


Within PHP there are seven functions used for searching strings using Perl-style regular expressions:

• preg_match() -
                         This function utilizes the Perl-style regular expressions to search strings provided for
a match. If there is a match, the function returns a TRUE, if the regular expression does not find a
match, a FALSE is returned.

<?php
$phone_number = "1900Atlanta";
if (preg_match("/.\D/",$phone_number)) print "The Phone
Number must contain only numeric digits";
?>

• preg_grep() -
                       This function is similar to the preg_match() function, but works only on arrays. The
preg_grep() function is also useful in that it creates a new array based on those matches found in the
search array.

<?php
$product_codes = ("NZ3456", "SUS5678", "SNZ3294", "US4678");
$NZ_Codes = preg_grep("/NZ/", $product_codes);
print_r($NZ_Codes); //NZ3456 and SNZ3294 are displayed
?>

The preg_grep() function can also take a third input parameter that has a unique capability. By
placing the words PREG_GREP_INVERT in the third input parameter, only those elements that do
not match the parameter searched for are returned. Using the example above, the opposite elements
would be returned:

<?php
$product_codes = ("NZ3456", "SUS5678", "SNZ3294", "US4678");
$non_nz_Codes = preg_grep("/NZ/", $product_codes,
PREG_GREP_INVERT);
print_r($non_nz_Codes); // SUS5678and US4678are displayed
?>
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