这段php代码详细演示了如何打开文件、读取文件和关闭文件，php中可以通过fopen打开文件，通过filesize函数获取文件大小，fread读取文件内容，fclose关闭文件
<html>
<head>
<title>Reading a file using PHP</title>
</head>
<body>
<?php
$filename = "/home/user/guest/tmp.txt";
$file = fopen( $filename, "r" );
if( $file == false )
{
echo ( "Error in opening file" );
exit();
}
$filesize = filesize( $filename );
$filetext = fread( $file, $filesize );
fclose( $file );
echo ( "File size : $filesize bytes" );
echo ( "<pre>$filetext</pre>" );
?>
</body>
</html>
