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Hàm strspn() trong PHP

Hướng dẫn cách sử dụng hàm strspn() trong lập trình PHP

Tác dụng của hàm strspn()

The strspn() function returns the number of characters present in the initial part of the string that contains only characters specified in the mask (list of allowable characters).

The following table summarizes the technical details of this function.

Return Value: Returns the length of the initial portion of the string that consist entirely of characters contained within the given mask.
Version: PHP 4+

Syntax

The basic syntax of the strspn() function is given with:

strspn(string, mask, start, length);

The following example shows the strspn() function in action.

<?php
// Sample string
$str = "Hello World!";

// Defining mask
$mask = "Hi";

// Find length of initial portion of string matching mask
echo strspn($str, $mask);
?>

Parameters

The strspn() function accepts the following parameters.

Parameter Description
string Required. Specifies the string to work on.
mask Required. Specifies the string containing every allowable characters.
start Optional. Specifies the position in the string to start searching.
length Optional. Specifies the portion of the string to search.

More Examples

Here're some more examples showing how strspn() function actually works:

If string does not start with any characters specified in the mask, this function returns 0.

<?php
echo strspn("Hello World!", "Wow");
?>

The following example returns the length of the initial portion of the string that consists only of characters contained within "Her". Let's try it out and see how it works:

<?php
echo strspn("Hello World!", "Her");
?>

In the following example only the portion "World" of the string will be examined, because the position to start searching is 6 and the length of the string to search is 5.

<?php
echo strspn("Hello World!", "Wow", 6, 5);
?>

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