您可以使用strpos和strrpos

$bStartsWith = strpos($sHaystack, $sNeedle) == 0;
$bEndsWith = strrpos($sHaystack, $sNeedle) == strlen($sHaystack)-strlen($sNeedle);

最近，我通常使用下划线php这样的库。

require_once("vendor/autoload.php"); //use if needed
use Underscore\Types\String; 

$str = "there is a string";
echo( String::startsWith($str, 'the') ); // 1
echo( String::endsWith($str, 'ring')); // 1   

图书馆里还有很多其他方便的功能。

我意识到这已经完成，但您可能需要查看strncmp，因为它允许您将字符串的长度与之进行比较，因此：

function startsWith($haystack, $needle, $case=true) {
    if ($case)
        return strncasecmp($haystack, $needle, strlen($needle)) == 0;
    else
        return strncmp($haystack, $needle, strlen($needle)) == 0;
}    

上面的正则表达式函数，但上面还建议了其他调整：

 function startsWith($needle, $haystack) {
     return preg_match('/^' . preg_quote($needle, '/') . '/', $haystack);
 }

 function endsWith($needle, $haystack) {
     return preg_match('/' . preg_quote($needle, '/') . '$/', $haystack);
 }

这里有一个针对PHP4的有效解决方案。如果在PHP5上使用substra_compare而不是strcasecmp（substr（…）），可以获得更快的结果。

function stringBeginsWith($haystack, $beginning, $caseInsensitivity = false)
{
    if ($caseInsensitivity)
        return strncasecmp($haystack, $beginning, strlen($beginning)) === 0;
    else
        return strncmp($haystack, $beginning, strlen($beginning)) === 0;
}

function stringEndsWith($haystack, $ending, $caseInsensitivity = false)
{
    if ($caseInsensitivity)
        return strcasecmp(substr($haystack, strlen($haystack) - strlen($ending)), $haystack) === 0;
    else
        return strpos($haystack, $ending, strlen($haystack) - strlen($ending)) !== false;
}

2016年8月23日更新

功能

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;
}

测验

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";
}

结果（PHP 7.0.9）

（从最快到最慢排序）

strncmp_startswith2: 40.2 ms
strncmp_startswith: 42.9 ms
substr_compare_startswith: 44.5 ms
substr_startswith: 48.4 ms
strpos_startswith: 138.7 ms
preg_match_startswith: 13,152.4 ms

结果（PHP 5.3.29）

（从最快到最慢排序）

strncmp_startswith2: 477.9 ms
strpos_startswith: 522.1 ms
strncmp_startswith: 617.1 ms
substr_compare_startswith: 706.7 ms
substr_startswith: 756.8 ms
preg_match_startswith: 10,200.0 ms

启动基准.php