php 获取上传文件后缀

$file = $_FILES['file']['name'];
$path_info = pathinfo($file);
$extension = $path_info['extension']; // 获取文件后缀名
echo $extension;

$file = $_FILES['file']['name'];
$extension = end(explode('.', $file)); // 获取文件后缀名
echo $extension;

$file = $_FILES['file']['name'];
preg_match("/\.[^.]+$/", $file, $matches);
$extension = $matches[0]; // 获取文件后缀名
echo $extension;

<?php
if ($_FILES['file']['error'] === UPLOAD_ERR_OK) {
    $file = $_FILES['file']['name'];
    $path_info = pathinfo($file);
    $extension = $path_info['extension']; // 获取文件后缀名
    echo "文件后缀名: " . $extension;

    // 移动上传的文件到指定目录
    $upload_dir = 'uploads/';
    if (!file_exists($upload_dir)) {
        mkdir($upload_dir, 0777, true);
    }
    $target_file = $upload_dir . basename($file);
    if (move_uploaded_file($_FILES['file']['tmp_name'], $target_file)) {
        echo "文件上传成功！";
    } else {
        echo "文件上传失败！";
    }
} else {
    echo "上传错误：" . $_FILES['file']['error'];
}
?>