A file,but different output,When using different functions:readfile,fread

[abalfazl]

Hello my firends

<?php
/* Open a test file for writing */
$fp = fopen("test.txt", "w+");
/* Apply the ROT13 filter to the
 * write filter chain, but not the
 * read filter chain */
stream_filter_append($fp, "string.rot13",
STREAM_FILTER_WRITE);
/* Write a simple string to the file
 * it will be ROT13 transformed at the end of the
stream operation
 * way out */
fwrite($fp, "This is a test\n"); // string data is
//first written, then ROT13 tranformed and lastly
//written to file*/
/* Back up to the beginning of the file */
rewind($fp);
$contents=fread($fp,512);
readfile("test.txt");

fclose($fp);
echo $contents;
?>

The output is:

Guvf vf n grfg
This is a test


When we use readfile(),It prints:

Guvf vf n grfg

But,When we use fread(),It prints:

This is a test

Why?

[yjanse]

Doesn't it overwrite? With mode 'w+' the filepointer is put at the beginning of the file. Maybe it will work better if you use 'a+', then the filepointer will be at the end of the file, in append-mode.