Simple PHP regular expression question

Question

What's the most efficient preg_match regular expression for the following:

1. The regular expression must match a certain string (case insensitive)
2. Can be followed by [ or ; and then something else

These are the test cases for "foo":

• foo --> good
• food --> bad
• foo; --> bad, need something after ;
• FOO;bar --> good
• foo[bar] --> good
• foo[ --> bad, need something after ]
• fOo[bar]1;2;3 --> good

This is my test code:

<?php

$tests = array();
$tests[] = 'foo';
$tests[] = 'food';
$tests[] = 'foo;';
$tests[] = 'FOO;bar';
$tests[] = 'foo[bar]';
$tests[] = 'foo[';
$tests[] = 'foo[]';
$tests[] = 'fOo[bar]1;2;3';

foreach ($tests as $test)
{
    echo $test, ' --> ';
    $found = preg_match('REGULAR EXPRESSION HERE', $test);
    if ($found === false || $found < 1)
        echo 'bad';
    else
        echo 'ok';
    echo '<br>', PHP_EOL;
}

?>

Answer 1

You can try this regex :

/foo(;.+?|\[.+?\].*?)*$/i

If your bracket doesn't need to be closed :

/foo([;\[].+?)*$/i

If your bracket or semicolon must not be the last part of your expression :

/foo([;\[][^;\[]+)*$/i

All passed the tests with Regex planet.

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Resources :

• www.regular-expressions.info

Answer 2

Simple:

/foo($|[[;].)/i