How to open php file php file operation

<pre name="code" class="php"><?php
//文件上传

if(isset($_POST[&#39;submit&#39;])){
	//文件大小
	$filesize=$_FILES[&#39;file&#39;][&#39;size&#39;];
	//文件名称
	$name=$_FILES[&#39;file&#39;][&#39;name&#39;]; 
	//将文件名重新编码
	$filename = iconv(&#39;utf-8&#39;,&#39;gbk&#39;,$name); 
	//文件存放路径
	$url=&#39;data/&#39;;
	//判断源文件名称是否为空（判断是否已经选择上传的文件）
	if($filename!=""){

		//判断该文件上传的错误代码数
		if($_FILES[&#39;file&#39;][&#39;error&#39;]>0){
			echo"文件上传失败，请重试！";
			}else{
			/*
			*$_FILES['file']['tmp_name']文件上传后在服务器端存储的临时文件名
			*/
			if(move_uploaded_file($_FILES['file']['tmp_name'],$url.$filename))
			{
				echo $filesize;
			echo "文件上传成功！";
		}else{
			echo "文件上传失败，请重试！";
			}
			}
			}else{
			echo "请选择要上传的文件！";
			}
		}
		
		//文件删除
		if(isset($_POST['del'])){
			//文件大小
			$filesize=$_FILES['file2']['size'];
			//文件名称
			$filename=$_FILES['file2']['name'];
			//文件存放路径
			$url='data/';
			$delfile=$url.$filename;
			//将路径重新编码
			$delfile = iconv('utf-8','gbk',$delfile); 
			//找寻文件
			if (file_exists ($delfile)) {
  			if(unlink($delfile)){
					echo "删除成功";
					}
 				}	
			}
			
			//文件名修改
			if(isset($_POST['update'])){
				//文件大小
				$filesize=$_FILES['file3']['size'];
				//文件名称
				$filename=$_FILES['file3']['name'];
				//文件存放路径
				$url='data/';
				$delfile=$url.$filename;
				//将路径重新编码
				$delfile = iconv('utf-8','gbk',$delfile); 
				//从表单获取新文件名
				$newName=$_POST['newname'];
				$newfilename=$url.$newName;
					//从新编码
					$newfileName=iconv('utf-8','gbk',$newfilename); 
					if(rename($delfile,$newfileName)){
						echo "修改成功！";
						}
				}
		?>
		<meta c/html"; charset="utf8" http-equiv="content-type">
		<!--enxtype规定在提交表单时要使用那种内容类型-->
		<form action="" method="post" enctype="multipart/form-data">
		<label>文件上传</label>
		<br/>
		<input type="file" name="file">
		<input type="submit" name="submit" value="上传">
		<br/>
		<label>文件删除</label>
		<br/>
		<input type="file" name="file2">
		<input type="submit" name="del" value="删除">
		<br/>
		<label>文件重命名</label>
		<br/>
		<input type="file" name="file3">
		<label>更改的文件名：</label>
		<input type="text" name="newname">
		<input type="submit" name="update" value="修改">
		</form>

The above introduces how to open PHP files and PHP file operations, including how to open PHP files. I hope it will be helpful to friends who are interested in PHP tutorials.