editing values stored in each subarray of an array

I am using the following code which lets me navigate to a particular array line, and subarray line and change its value.

What i nee开发者_运维技巧d to do however, is change the first column of all rows to BLANK or NULL, or clear them out.

How can i change the code below to accomplish this?

<?php
$row = $_GET['row'];
$nfv = $_GET['value'];
$col = $_GET['col'];

$data = file_get_contents("temp.php");
$csvpre = explode("###", $data);
$i = 0;
$j = 0;

if (isset($csvpre[$row]))
{
  $target_row = $csvpre[$row];
  $info = explode("%%", $target_row);
  if (isset($info[$col]))
  {
     $info[$col] = $nfv;
  }
  $csvpre[$row] = implode("%%", $info);
}


$save = implode("###", $csvpre);
$fh = fopen("temp.php", 'w') or die("can't open file");
fwrite($fh, $save);
fclose($fh);
?>

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Use foreach or array_map to perform the same action on all elements of an array.

In this case, something roughly along these lines?

foreach($rows as &$row) {
    $row[0] = NULL;
}

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I don't have a ready answer for you but I would recommend checking out CakePHP's Set class. It does things like this very well and (in some methods) supports XPath. Hopefully you can find the code you need there.

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Depending on the size of that file, this could be much more efficient than looping through:

$data = file_get_contents("temp.php"); //data = blah%%blah%%blah%%blah%%###blah%%blah%%blah
$data = preg_replace( "/^(.+?)(?=%%)/", "\\1", $data ); //Replace first column to blank
$data = preg_replace( "/(###)(.+?)(?=%%))/", "\\1", $data ); //Replace all other columns to blank

After that, write it back to the file as you did above.

This would need to be adjusted to allow for escape characters if your columns allow %% to appear consecutively within them, but other than that, this should work.

If you expect this csv file to get REALLY large, you should start thinking of looping through the file line by line rather than reading it completely into memory using file_get_contents. I would point you to fgets_csv, but I don't believe it is possible to get each csv line by any delimiter other than newline (unless you are willing to replace your ### separator with \r\n). If you end up going this way, the answer totally changes :P

For more information on Regex (specifically positive lookaheads) see Regex Tutorial - Lookahead and Lookbehind Zero-Width Assertions (also a great site for regex in general)