A fputs & fgets problem

[pengyang]

I wrote a program to test the function fputs() & fgets():
<?
$fp = fopen("d:\php.doc\1.txt", "r+");
fputs($fp,"haha\n");
$out=fgets($fp,1000);
fputs($fp,"hehe\n");
$out=fgets($fp,1024);
fclose($fp);
?>
I think the result is:
haha
hehe
But the result of 1.txt is:
haha- cho "Hello!"
hehe= fopen("d:\php.doc\1.txt", "r+");

I don't know why.
thanks.

[chaostik]

Alfred,

One point to note is that the file 1.txt must already exist already, because "r+" will not create it if it does not. You should use "a+" or "w+" if you think the file may not already exist. As you will see later, I recommend the latter.

Now I created 1.txt as an empty file and ran this script on a Linux system (getting rid of the "d:\php.doc\" part obviously). The output was as per your prediction, as I would have expected it to be. The only possible explanation I can think of is that 1.txt already exists and has data in it. If that is the case then what is happening is this:

1.txt has contents like this (where * represents an unknown character):

*- cho "Hello!"
*=fopen("d:\php.doc\1.txt", "r+");

Following the script through:

-> The fopen opens the file and places the file pointer at the start of the file. Note that the file is not truncated ... it's contents are left in tact.

-> The first fputs will write "haha" over the first 4 characters in the file.

-> The following fgets will read into $out the rest of the first line of 1.txt, so I predict $out would contain: '- cho "Hello!"'

-> The file pointer is now at the start of the second line of text in the file.

-> Therefore the next fputs will write over the first 4 characters of the second line with "hehe".

-> The second fgets does as per the first and just takes you to the end of that second line.

-> Your fclose finishes off the script and safely releases the file descriptor.

I hope you follow the angle I'm coming from!

All the best,

Louis

[pengyang]

I try another time on the win2000P system.This time I modify the script:
<?
$fp = fopen("d:\1.txt", "w+");
fputs($fp,"haha\n");
$out=fgets($fp,1000);
fputs($fp,"hehe\n");
$out=fgets($fp,1024);
fclose($fp);
?>
And the 1.txt doesn't exist.
But the result is:
haha
, = fopen("d:\1.txt", "w+");
hehe
s($fp,"haha\n");