php 限制字符数

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>限制字符数示例</title>
    <script>
        function checkLength(input) {
            var maxLength = 10;
            if (input.value.length > maxLength) {
                input.value = input.value.substring(0, maxLength);
            }
        }
    </script>
</head>
<body>
    <form>
        <input type="text" oninput="checkLength(this)" placeholder="最多输入10个字符">
        <button type="submit">提交</button>
    </form>
</body>
</html>

<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $input = $_POST['input'];
    $maxLength = 10;

    if (strlen($input) > $maxLength) {
        $input = substr($input, 0, $maxLength);
    }

    // 处理输入数据
    echo "处理后的输入: " . htmlspecialchars($input);
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>限制字符数示例</title>
</head>
<body>
    <form method="post">
        <input type="text" name="input" placeholder="最多输入10个字符">
        <button type="submit">提交</button>
    </form>
</body>
</html>