writing in the middle of a file

amduser

Hi,

I need to write s string in the middle of the file.

I can't seem to do this the C++ way ( using the file pointer ) as ftell seems to go haywire.

Whatever I fwrite() seems to be appended at the end of the file.

If if open the file on the 'w' mode , everything gets truncated.

Anyone have a solution for this ? I need to write append in between the file without doing a file overwrite.

Thanks ,

p.s. When I open a file in the 'a' or 'a+' mode , a ftell() displays the file pointer at 0 and not at the end of the file. Any idea why this happens ?

laserlight

Read into a string, then append your string to the correct portion.

amduser

Thats the problem. I can't append a string into any poition exceptin the end.

laserlight

$str = "some text";
$contents = file_get_contents($filename);
// put $str right in the middle of $contents
$loc = (int)(strlen($contents) / 2);
$contents = substr($contents, 0, $loc) . $str . substr($contents, $loc);
// only for PHP5, use other ways to write for PHP4
file_put_contents($filename, $contents);

amduser

AYe , I've already done that .

I need to do the same thing using the file pointer . i.e fwrite($fp,$str)...that sorta thing.

Any way to do that ?

laserlight

I need to do the same thing using the file pointer . i.e fwrite($fp,$str)...that sorta thing.

As far as I know, you cannot. The problem is that if you write to the middle of the file, you will overwrite the content that comes after point where you start writing. I dont think opening in append mode will change that (though I could be wrong).

amduser

I just needed someone to confirm that. Thanks. The overwriting part wasn't the problem , i've a loop to take care of that ( via storing in buffer) . IT seems that you cannot write in between at all , unless u overwrite the file.

Atleast thats the problem in php 4.3

The file ppointer concept seems to be seriously flawed. The only solutio I could work was close to usrs.

Open the file and read the values

file("filename")

store the oldtext on a buffer
then open the file again in the 'w' mode ( hence truncating ...)

and then place ur new data first and then the old , hence working on append principle.

Same procedure to add in between.

Thanks mate!