Read odd lines in text file

james_cwy

Say, does anyone know how I can open a file in php and just read and display the odd lines only because that is where the important data is?

This is what I would like to do actually:
Read from the text file, only odd no lines.
Read from table
Compare odd line with records in table
if already in table break
else insert it
**Note:The data at the odd lines may be repeated

eg. aaaaaaaaaaaaaaaaa
xxxxxxxxxxxxxxxxxxxxxxx
bbbbbbbbbbbbbbbbbbbb
xxxxxxxxxxxxxxxxxxxxxxx
ccccccccccccccccccccccc
xxxxxxxxxxxxxxxxxxxxxxx
bbbbbbbbbbbbbbbbbbbb

Important is a, b,c-the xxxxx not important
First read the odd line from text file.
If is not in the table, insert. For it to be able to insert, it needs to check the whole table.
The issue arises when it comes to te second line of bbb.
Once it finds that there is already a record bbbb in the table. It should stop and continue with the next odd line from the text file.
I am not sure how to do this.

Hope someone can help me out here. I am new at programming.
Thanks a million.

rheroux

Well, here's something to start you off.


<?php

$file = "file.txt";

$handle = fopen($file,"r+b") or die ("Could not open file $file");

$odd_num_array = array();

$i = 0;

while (!feof ($handle)) {
    $string = fgets($handle, 4096);
if((1&$i))
{
$odd_num_array[] = $string;
}
$i++;

}


?>

Now, the first line is counted as 0 because we set $i = 0. If you're taking the first line to be an odd numbered line, then simply set $i = 1 instead.

You can then use the array to execute your queries based on whether the line is in the table or not.

james_cwy

Thanks I will try it

james_cwy

How should I use echo and display it?

rheroux

Use a for loop to display the contents of the array.


for($i = 0; $i < count($odd_num_array); $i++)
{

echo $odd_num_array[$i]."<br>";

}

james_cwy

If I would like to read the even lines, what do I need to change?

THanks
James

Mordecai

If I were you, I'd use file(). Uses more memory (so don't do this if you have a large file!), but makes it a hell of a lot easier. 🙂

$lines = file('file.txt');
for ($i=0;$i<count($lines);$i++) {
  if ($i % 2) {
    // It's even
    echo $lines[$i];
  }
  else {
    // It's odd
  }
}

james_cwy

After trying multiple combinations, I managed to read the even lines of the text files.
Consider the previous question void.

Thanks anyway
James