Deleting a line from a flat file

fr600

I'm having a difficult time deleting a line from a flat file. I'm hoping that one of you guys can help me with this.

Let's say I have a flat file "database.txt" which contains the following line:

This is line 1
This is line 2
This is line 3
This is line 4
This is line 5
This is line 6
This is line 7
This is line 8

Now, I want to delete, lets say, "This is line 4". How can I do it? Please help me.

Thanks

etully

The only way to do it is to read in all the lines and then write them out one at a time - except don't write out the line that you want to delete.

MarkR

Doing this in a web application when other threads could be accessing the file is a recipe for disaster. You can get it right with proper locking and/or by using atomic file operations (hint: renaming a file is atomic on most OSs), but it's not easy.

Mark

fr600

etully wrote:
The only way to do it is to read in all the lines and then write them out one at a time - except don't write out the line that you want to delete.

Thanks but I want to know how to do it.

bradgrafelman

$data = file('myfile.txt');
if($key = array_search('This is line 4', $data))
    unset($data[$key]);
$data = implode('', $data);

That would remove the line from the file... I'll leave writing the contents back into the file up to you.

fr600

Thanks, I'm gonna try this.