The role of strpos in php

strpos() function is used in PHP to find the first occurrence of a specified substring in a string and return its index (starting from 0). If the substring is not found, -1 is returned. Usage: strpos($haystack, $needle, $offset = 0).

The role of strpos in PHP

In PHP, the strpos() function is used to find in a string Specifies the first occurrence of the substring.

Usage

strpos() function has the following syntax:

<code class="php">int strpos(string $haystack, string $needle, int $offset = 0)</code>

• $haystack: Characters to search for string.
• $needle: The substring to be found.
• $offset (optional): Which index position in the string to start searching from. The default value is 0, which means the search starts at the beginning of the string.

Return results

• If the substring is found in the string, the strpos() function returns the substring for the first time in the string The position where it appears (starting from 0).
• If the substring is not found, -1 is returned.

Example

The following example demonstrates the use of the strpos() function:

<code class="php">$string = "Hello World!";

// 查找子字符串 "World" 在字符串中的位置
$position = strpos($string, "World");

// 输出结果
echo $position; // 输出：6</code>

In this example, the strpos() function finds The position of the first occurrence of the substring "World" in the string (index 6).

Note

• When using the strpos() function, case sensitivity means that "World" and "world" will be treated differently substring.
• If $needle is an empty string, the strpos() function will return 0.
• If $offset is greater than the length of the string, the strpos() function will return -1.

The above is the detailed content of The role of strpos in php. For more information, please follow other related articles on the PHP Chinese website!