Deleting Lines from a Text File

[Anon]

Hi there,

I'm using a simple text file for light database duty (I lack access to MySQL at the moment), and I have one problem.

First, let me give an idea of how it's set up:

Item Item2 Item3
Item Item2 Item3
Item Item2 Item3

And so on, with the spaces being tabs. What I want is this:

When there are more then 10 such lines in the text file, the last line will be deleted, taking the number back down to 10. I know this ought to be simple, but manipulating text files really isn't my strong point. If someone could give me an idea of what this would look like in code, I'd be very grateful.

Cheers,
Peter

[Anon]

Use file() to read your file into a PHP array. (one line per element)
Use count() to count how many elements there are (and therefore how many lines).
If more than ten, use fopen() to open the file for writing (thus erasing the old data)
Use a while/for loop to print the first 10 elements from the array into the file.

Et presto.

Note: don't forget to check the newline characters!

[Anon]

Vincent,

Thanks! However, I'm not sure I'm getting it. Based on your message, I constructed a little function called TestNews() and ran it against a file called "test.txt" which had around 30 lines in it. However, all this function seems to do is empty the file, and I can't tell why. Here's the function:

function TestNews()
{
$NewsFile = file("test.txt"); // Read contents of file into array
$LineNum = count($NewsFile); // Count items in array
PRINT($LineNum); // Print that number (DEBUG)
if ($LineNum > 10) // Check to see if there are more than 10 items
{
$TheFile = fopen("test.txt", "w"); // Open/erase the file
$LineCounter = 0; // Init the counter
while ($LineCounter < 11);
{
fwrite($TheFile, $NewsFile[$LineCounter]); // Write items back in, one line at a time
PRINT($)
$LineCounter = ($LineCounter + 1);
}
fclose($TheFile); // Close the file
}
}

[Anon]

Uhm... well... lets see... giggle

you have a ";" after your while statement.

Loops and IFs don't allways need the {} to define what should be done in the loop or the IF.
If you leave out the {}, then the statements upto the next ";" is executed.

so:
IF (1==1) echo "hi";

will print "hi" if 1==1.

and
while ($t<10) ;

will do nothing while $t<10
and because it does nothing, $t will never ever be >10.
You can prevent irritating errors like these by doing:
while ($t++<10)

this will check if $t<10 and then autiomatically increase $t by one.
Thus it will allways get over 10 at some point in time.

Oh, and notice my use of 10 instead of 11.
You start your count at zero.
Starting at zero, there are 11 numbers before you get to 11.
0,1,2,3,4,5,6,7,8,9,10. thats 11 numbers, so it will print 11 lines.