简而言之：

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

function endsWith($str, $needle){
   $length = strlen($needle);
   return !$length || substr($str, - $length) === $needle;
}

简而言之：

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

function endsWith($str, $needle){
   $length = strlen($needle);
   return !$length || substr($str, - $length) === $needle;
}

这是一个接受答案的多字节安全版本，它适用于UTF-8字符串：

function startsWith($haystack, $needle)
{
    $length = mb_strlen($needle, 'UTF-8');
    return (mb_substr($haystack, 0, $length, 'UTF-8') === $needle);
}

function endsWith($haystack, $needle)
{
    $length = mb_strlen($needle, 'UTF-8');
    return $length === 0 ||
        (mb_substr($haystack, -$length, $length, 'UTF-8') === $needle);
}

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

PHP 8.0及更高版本

从PHP 8.0开始，您可以使用

str_starts_with手册和

str_ends_with手动

实例

echo str_starts_with（$str，'|'）；

8.0之前的PHP

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;
}

还可以使用正则表达式：

function endsWith($haystack, $needle, $case=true) {
  return preg_match("/.*{$needle}$/" . (($case) ? "" : "i"), $haystack);
}