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str_starts_with

(PHP 8)

str_starts_with — Checks if a string starts with a given substring

Descripción

str_starts_with(string $haystack, string $needle): bool

Performs a case-sensitive check indicating if haystack begins with needle.

Parámetros

haystack: The string to search in.
needle: The substring to search for in the haystack.

Valores devueltos

Returns true if haystack begins with needle, false otherwise.

Ejemplos

Ejemplo #1 Using the empty string ''

<?php
if (str_starts_with('abc', '')) {
    echo "All strings start with the empty string";
}
?>

El resultado del ejemplo sería:

All strings start with the empty string

Ejemplo #2 Showing case-sensitivity

<?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';
}

?>

El resultado del ejemplo sería:

The string starts with 'The'
"the" was not found because the case does not match

Notas

Nota: Esta función es segura binariamente.

Ver también

str_contains() - Determine if a string contains a given substring
str_ends_with() - Checks if a string ends with a given substring
stripos() - Encuentra la posición de la primera aparición de un substring en un string sin considerar mayúsculas ni minúsculas
strrpos() - Encuentra la posición de la última aparición de un substring en un string
strripos() - Encuentra la posición de la última aparición de un substring insensible a mayúsculas y minúsculas en un string
strstr() - Encuentra la primera aparición de un string
strpbrk() - Buscar una cadena por cualquiera de los elementos de un conjunto de caracteres
substr() - Devuelve parte de una cadena
preg_match() - Realiza una comparación con una expresión regular

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User Contributed Notes 3 notes

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Paul Phillips ¶

3 years ago


You can use this in PHP versions less than 8.

<?php
function str_starts_with ( $haystack, $needle ) {
  return strpos( $haystack , $needle ) === 0;
}

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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.

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Reinder ¶

2 years ago


In PHP7 you may want to use:

if (!function_exists('str_starts_with')) {
  function str_starts_with($str, $start) {
    return (@substr_compare($str, $start, 0, strlen($start))==0);
  }
}

AFAIK that is binary safe and doesn't need additional checks.

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