[RESOLVED] FIND AND REPLACE LINE IN FLAT FILE

[DaleRobbins]

I have a program which keeps a record of users in a flat text file DB. I need to locate a specific line of data, based on a key field identifier, and replace the entire line with a different line of data. In other words, I wish to swap one line with another. The new line must remain in the same position as the one it replaces.

Each line of data is a single record that contains 21 fields, delimited by pipe. The last field $field[20] is the identifier.

SAMPLE DB

Billy Bob|1234 Hillbilly Way|Loudholler|TN|37024||123-456-6789|[e-mail]||Category 1|BIG TEST TO SEE IF THIS WORKS!|This is a test.|02/12/2010|0|ok|billywilly|60||||101
Dan Boone|4321 Coon Skin Road|Whoopass|KY|43265||123-456-6789|[e-mail]||Category 4|NUTHER TEST TO SEE IF THIS WORKS!|This is a nuther test.|01/18/2010|0|ok|boonbaby|60||||102
David Crocket|2468 Hillbilly Way|Whoowee|VA|37024||123-456-6789|[e-mail]||Category 6|FINAL TEST TO SEE IF THIS WORKS!|This is a final test.|01/06/2010|0|ok|pocketrocket|60||||103

Here is the simple code I now use to locate and display a line based on key identifier.

<?php
$key = "102";  //key identifier for field 20

 //Below is a sample replacement line
$replacestring = "Willy Nilly|4250 Hounddog Blvd|Plains|GA|54234||123-456-6789|[e-mail]||Category 4|REPLACE TEST TO SEE IF THIS WORKS!|This is a replacement test.|02/28/2010|0|ok|rogerwilco|60||||120";

$handle = fopen("data.txt", "r");

While (!feof($handle)){

  $line = fgets($handle);

  $field = explode('|', trim($line));

  $gluedfield = implode("|", $field);

  if($key ==$field[20]) {

echo "$gluedfield\n";


  }

}
?>

I would appreciate any assistance that you might be able to offer on this. Thank you!

(By the way, no suggestions about the preferable use of mySQL is necessary. I already use DB's elsewhere, but it is not available for this particular script. )

[NogDog]

You could use a temporary file to make a copy of the file, changing the applicable line, then copying it over the original file, something like:

$key = "102"; //key identifier for field 20
//Below is a sample replacement line
$replacestring = "Willy Nilly|4250 Hounddog Blvd|Plains|GA|54234||123-456-6789|[e-mail]||Category 4|REPLACE TEST TO SEE IF THIS WORKS!|This is a replacement test.|02/28/2010|0|ok|rogerwilco|60||||120";

$handle = fopen("data.txt", "r");
$tempFile = tempnam('.', 'tmp_');
$tempHandle = fopen($tempFile, 'w');
While (!feof($handle)) {
   $line = fgets($handle);
   $field = explode('|', trim($line));
   if (array_key_exists(20, $field) && $key == $field[20]) {
      $line = trim($replacestring) . "\n";
   }
   fputs($tempHandle, $line, strlen($line));
}
fclose($handle);
fclose($tempHandle);
unlink($tempFile);

[DaleRobbins]

Looks like a promising idea... but I can't seem to get it to work. The script processes but it doesn't write anything to the data.txt file. Keep in mind while there are 21 fields they are numbered 0 - 20.

[NogDog]

Oops...I forgot the [man]copy/man part. After the two fclose() lines and before the unlink(), you need:

copy($tempFile, 'data.txt');

[DaleRobbins]

That works very nicely! Thank you kindly for taking your time to assist! I appreciate it much.

[NogDog]

You might want to add a little defensive coding: for instance, something to make sure that the temp file actually has some data in it before copying it over the original file. At least make sure that the temp file's filesize() is non-zero before doing the copy(), perhaps?

[DaleRobbins]

Great advice... I'll do that.

[DaleRobbins]

Hmmm... I thought would be a simple revision, but I can't seem to get this to work right either.

I tried this, but it didn't work. Do you have a better suggestion?

$size = filesize($tempFile);
if ($size < 0) {
echo "Temp file empty";
exit;
}

[NogDog]

Well, hopefully you never have < 0 bytes in a file. 😉

[DaleRobbins]

Ha... I have no idea where my mind was today. I guess I was feeling "less than" myself!

Well, this works a slight bit better! Thanks for not calling me stupid! :bemused:

$size = filesize($tempFile);
if ($size == 0) {
echo "Temp file empty";
exit;
}