无法使用php

Question

我在选择图像时形成，然后点击上传，现在只执行＆＃34;请选择一个文件＆＃34;请检查错误，因为我无法弄清楚。                上传文件
                                    上传一个文件：               在此处输入代码     点击立即上传                         

<?php
if(isset($_POST['submit'])) {
    $name=@$_FILES=['file']['name'];
    $type=@$_FILES=['file']['type'];
    $size=@$_FILES=['file']['size'];
    $tmp=@$_FILES=['file']['tmp_name'];
    if($name=='')
    {
        echo"<script>alert('please select a file') </script>";
        exit();
    }
    if(($type =="image/jpeg")||($type =="image/gif") ||($type =="image/png"))
    {
        if(file_exists("images/" .$_FILES["file"]["name"]))
        {
            echo"this file $name is already exist";
            exit();
        }
        if($size<=5000)
        {
            move_uploaded_file($tmp,"images/$name");
            echo "file was uploaded <img src='imges/$name'>";
        }
        else
        {
            echo "Size of image $size is larger then 50 kb";
        }
    }else
    {
        echo "$type This is not valid";
    }
}
?>
</body>
</html>