我想使用PHP自动重命名文件

Question

我希望代码自动重命名文件。因此，如果文件名为image.png，并且另一个用户上传了一个名为image.png的文件，则代码将自动将该文件重命名为image1.png，依此类推。

我当前的代码未上传图片。页面空白，并显示：“文件是图像-image / png。”。

if (isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if ($check !== false) {
        echo "File is an image - " . $check["mime"] . ".";
        $uploadOk = 1;
    } else {
        echo "File is not an image. ";
        $uploadOk = 0;
    }

    // Checks if file already exists, and if it does, it should rename it.

    while (!file_exists($target_file.".".$imageFileType)) {
        $target_file = $target_file.$i++;
        $uploadOk = 1;
    }

    // Checks file size
    if ($_FILES["fileToUpload"]["size"] > 500000000) {
        echo "Sorry, your file is too large. ";
        $uploadOk = 0;

        // Only allow specific file types
        if ($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg" && $imageFileType != "gif") {
            echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed, your uploaded a $imageFileType file. ";
            $uploadOk = 0;
        }
        // Checks if $uploadOk is set to 0 by mistake.
        if ($uploadOk == 0) {
            echo "Sorry, your file was not uploaded. ";

        // All is ok
        } else {
            if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
                echo "The file ". basename($_FILES["fileToUpload"]["name"]). " has been uploaded.";
            } else {
                echo "Sorry, there was an error uploading your file.";
            }
        }
    }
?>

我期望代码使用$ target_file并添加$ i ++。我期望它会一直增加数字，直到服务器上没有与它同名的文件为止。