php字符串匹配函数

<?php
$text = "Hello world, welcome to the universe.";
$search = "world";

// 区分大小写的查找
$position = strpos($text, $search);
if ($position !== false) {
    echo "Found at position: " . $position;
} else {
    echo "Not found.";
}

// 不区分大小写的查找
$position = stripos($text, $search, 0, true);
if ($position !== false) {
    echo "Found at position (case-insensitive): " . $position;
} else {
    echo "Not found (case-insensitive).";
}
?>

<?php
$text = "Hello world, welcome to the universe.";
$search = "World"; // 注意大小写

// 使用不区分大小写的查找
$position = stripos($text, $search);
if ($position !== false) {
    echo "Found at position (case-insensitive): " . $position;
} else {
    echo "Not found (case-insensitive).";
}
?>

<?php
// 使用正则表达式进行搜索
$text = "Hello world, welcome to the universe.";
$search = "world";

if (preg_match("/$search/i", $text, $matches)) {
    echo "Found.";
} else {
    echo "Not found.";
}
?>