Understanding PHP stripos() Function: Syntax, Parameters, Return Values, and Examples

In PHP, the stripos() function is a case-insensitive string search function that finds the position of the first occurrence of a needle within a haystack.

Syntax

<code>int stripos ( string $haystack , mixed $needle [, int $offset = 0 ] )</code>

Parameters

$haystack : The string to search in.

$needle : The string to search for.

$offset (optional): The position in $haystack to start searching from; default is 0.

Return value

If the $needle is found, stripos() returns its position (starting from 0); otherwise it returns false .

Examples

Example 1: Basic search

<code>$str = "Hello, World!";
$pos = stripos($str, "world");
if ($pos !== false) {
    echo "字符串 'world' 在位置 $pos 处找到。";
} else {
    echo "未找到字符串 'world'。";
}</code>

Output: 字符串 'world' 在位置 7 处找到。

Example 2: Search with offset

<code>$str = "Hello, World!";
$pos = stripos($str, "o", 5);
if ($pos !== false) {
    echo "字符 'o' 在位置 $pos 处找到。";
} else {
    echo "未找到字符 'o'。";
}</code>

Output: 字符 'o' 在位置 8 处找到。

Example 3: Searching multiple substrings

<code>$str = "Hello, World!";
$keywords = array("hello", "world");
foreach ($keywords as $keyword) {
    $pos = stripos($str, $keyword);
    if ($pos !== false) {
        echo "字符串 '$keyword' 在位置 $pos 处找到。";
    } else {
        echo "未找到字符串 '$keyword'。";
    }
    echo "<br>";
}</code>

Output:

字符串 'hello' 在位置 0 处找到。

字符串 'world' 在位置 7 处找到。

Summary

The stripos() function is a useful, case-insensitive string search tool in PHP, allowing developers to locate substrings efficiently, with optional offset control, and can be combined in loops to handle multiple keywords.

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