You can use this in PHP versions less than 8.
<?php
function str_starts_with ( $haystack, $needle ) {
return strpos( $haystack , $needle ) === 0;
}
str_starts_with
(PHP 8)
str_starts_with — 检查字符串是否以指定子串开头
参数
-
haystack -
在其中搜索的字符串。
-
needle -
要在
haystack中搜索的子串。
返回值
如果 haystack 以 needle 开头，返回 true，否则返回 false。
示例
示例 #1 使用空字符串 ''
<?php
if (str_starts_with('abc', '')) {
echo "All strings start with the empty string";
}
?>以上示例会输出：
All strings start with the empty string
示例 #2 展示大小写区分
<?php
$string = 'The lazy fox jumped over the fence';
if (str_starts_with($string, 'The')) {
echo "The string starts with 'The'\n";
}
if (str_starts_with($string, 'the')) {
echo 'The string starts with "the"';
} else {
echo '"the" was not found because the case does not match';
}
?>以上示例会输出：
The string starts with 'The' "the" was not found because the case does not match
注释
注意: 此函数可安全用于二进制对象。
参见
- str_contains() - 确定字符串是否包含指定子串
- str_ends_with() - 检查字符串是否以指定子串结尾
- stripos() - 查找字符串首次出现的位置（不区分大小写）
- strrpos() - 计算指定字符串在目标字符串中最后一次出现的位置
- strripos() - 计算指定字符串在目标字符串中最后一次出现的位置（不区分大小写）
- strstr() - 查找字符串的首次出现
- strpbrk() - 在字符串中查找一组字符的任何一个字符
- substr() - 返回字符串的子串
- preg_match() - 执行匹配正则表达式
add a note
User Contributed Notes 3 notes
Paul Phillips ¶
3 years ago
jgusta ¶
3 years ago
With credit to Paul Phillips for the original polyfill posted.
If you do not have PHP 8, you can use these functions to get the capability of the new string functions.
But! Remember to use a conditional check to make sure the function is not already defined.
<?php
// source: Laravel Framework
// https://github.com/laravel/framework/blob/8.x/src/Illuminate/Support/Str.php
if (!function_exists('str_starts_with')) {
function str_starts_with($haystack, $needle) {
return (string)$needle !== '' && strncmp($haystack, $needle, strlen($needle)) === 0;
}
}
if (!function_exists('str_ends_with')) {
function str_ends_with($haystack, $needle) {
return $needle !== '' && substr($haystack, -strlen($needle)) === (string)$needle;
}
}
if (!function_exists('str_contains')) {
function str_contains($haystack, $needle) {
return $needle !== '' && mb_strpos($haystack, $needle) !== false;
}
}
?>
This keeps it from breaking in case you upgrade and forget that you added it. This is a good practice generally when using the global scope for your helper functions.
