Use PHP to check if a string starts with, ends with or contains another string

PHP makes working with strings quite easy but if you simply want to check if a string starts with, ends with or contains another string there are no functions that give you a simple true or false.

So, here they are. To understand what mb_internal_encoding('UTF-8'); does and why you should use it read my earlier blog post “What you need to know about PHP’s internal character encoding“.

<?php

function stringStartsWith($string, $subString, $caseSensitive = true) {

    if ($caseSensitive === false) {

        $string		= mb_strtolower($string);
        $subString  = mb_strtolower($subString);

    }

    if (mb_substr($string, 0, mb_strlen($subString)) == $subString) {

        return true;

    } else {

        return false;

    }

}

function stringEndsWith($string, $subString, $caseSensitive = true) {

    if ($caseSensitive === false) {

        $string		= mb_strtolower($string);
        $subString  = mb_strtolower($subString);

    }

    $strlen 			= strlen($string);
    $subStringLength 	= strlen($subString);

    if ($subStringLength > $strlen) {

        return false;

    }

    return substr_compare($string, $subString, $strlen - $subStringLength, $subStringLength) === 0;

}

function stringContains($haystack, $needle, $caseSensitive = true) {

    if ($caseSensitive === false) {

        $haystack	= mb_strtolower($haystack);
        $needle    	= mb_strtolower($needle);

    }

    if (mb_substr_count($haystack, $needle) > 0) {

        return true;

    } else {

        return false;

    }

}

mb_internal_encoding('UTF-8');

echo '<pre>';
echo 'Case-sensitive:';
var_dump(stringStartsWith('Foo bar', 'Fo')); // true
var_dump(stringStartsWith('Bar', 'Foo bar')); // false
var_dump(stringEndsWith('Foo bar', 'ar')); // true
var_dump(stringEndsWith('Foo bar', 'foo')); // false
var_dump(stringContains('Foo bar', 'o b')); // true
var_dump(stringContains('Foo bar', 'blah')); // false
echo PHP_EOL . 'Case-insensitive:' . PHP_EOL;
var_dump(stringStartsWith('FOO BAR', 'fo', false)); // true
var_dump(stringEndsWith('FOO BAR', 'ar', false)); // true
var_dump(stringContains('FOO BAR', 'o b', false)); // true
echo '</pre>';

?>