PHP 8.0 and higher

Since PHP 8.0 you can use the str_starts_with and the str_ends_with functions.

echo str_starts_with($str, '|');

PHP before 8.0

function startsWith( $haystack, $needle ) {     $length = strlen( $needle );     return substr( $haystack, 0, $length ) === $needle;}

function endsWith( $haystack, $needle ) {    $length = strlen( $needle );    if( !$length ) {        return true;    }    return substr( $haystack, -$length ) === $needle;}

You can use substr_compare function to check start-with and ends-with:

function startsWith($haystack, $needle) {    return substr_compare($haystack, $needle, 0, strlen($needle)) === 0;}function endsWith($haystack, $needle) {    return substr_compare($haystack, $needle, -strlen($needle)) === 0;}

^{This should be one of the fastest solutions on PHP 7 (benchmark script). Tested against 8KB haystacks, various length needles and full, partial and no match cases. strncmp is a touch faster for starts-with but it cannot check ends-with.}

Updated 23-Aug-2016

Functions

function substr_startswith($haystack, $needle) {    return substr($haystack, 0, strlen($needle)) === $needle;}function preg_match_startswith($haystack, $needle) {    return preg_match('~' . preg_quote($needle, '~') . '~A', $haystack) > 0;}function substr_compare_startswith($haystack, $needle) {    return substr_compare($haystack, $needle, 0, strlen($needle)) === 0;}function strpos_startswith($haystack, $needle) {    return strpos($haystack, $needle) === 0;}function strncmp_startswith($haystack, $needle) {    return strncmp($haystack, $needle, strlen($needle)) === 0;}function strncmp_startswith2($haystack, $needle) {    return $haystack[0] === $needle[0]        ? strncmp($haystack, $needle, strlen($needle)) === 0        : false;}

Tests

echo 'generating tests';for($i = 0; $i < 100000; ++$i) {    if($i % 2500 === 0) echo '.';    $test_cases[] = [        random_bytes(random_int(1, 7000)),        random_bytes(random_int(1, 3000)),    ];}echo "done!\n";$functions = ['substr_startswith', 'preg_match_startswith', 'substr_compare_startswith', 'strpos_startswith', 'strncmp_startswith', 'strncmp_startswith2'];$results = [];foreach($functions as $func) {    $start = microtime(true);    foreach($test_cases as $tc) {        $func(...$tc);    }    $results[$func] = (microtime(true) - $start) * 1000;}asort($results);foreach($results as $func => $time) {    echo "$func: " . number_format($time, 1) . " ms\n";}

Results (PHP 7.0.9)

(Sorted fastest to slowest)

strncmp_startswith2: 40.2 msstrncmp_startswith: 42.9 mssubstr_compare_startswith: 44.5 mssubstr_startswith: 48.4 msstrpos_startswith: 138.7 mspreg_match_startswith: 13,152.4 ms

Results (PHP 5.3.29)

(Sorted fastest to slowest)

strncmp_startswith2: 477.9 msstrpos_startswith: 522.1 msstrncmp_startswith: 617.1 mssubstr_compare_startswith: 706.7 mssubstr_startswith: 756.8 mspreg_match_startswith: 10,200.0 ms

startswith_benchmark.php