Best loop to use question

[rulkster2]

Wow. I haven't coded in years and I am a little bit rusty.

What is the best loop to use when I want to grab only certain rows(records). In the below example I am grabbing from a csc file that I am uploading and for now just displaying on the screen until I get it right and then it will dump into a database.

I want to start at record #48 and then grab every 3rd record from that point. 48,51,54,57, and so on.

This isn't working:

for ($i = 0; $i < 600; $i++) { // loop that goes through all the columns of 1 record. WORKING

 for ($c = 48; $c < 1000; $c+3) { // HERE IT IS, NOT WORKING
 echo "$data[$i] || ";
 }

}

Also, if I don't know the condition ($i<600, $c<1000) ending value, what would be the best to use. Right now I am just using a real high number that I know isn't going to be met.

Thanks!!!!!!!!!

[rulkster2]

FULL CODE:

$count = 0;
if ($_FILES[csv][size] > 0) {

//get the csv file
$file = $_FILES[csv][tmp_name];
$handle = fopen($file,"r");

//loop through the csv file and insert into database

  do {
         if ($data[0]) {


// print data


  for ($i = 0; $i < 600; $i++) { 


 if ($count == 48 { [B]// Display record 48, Then the next one I want is 51, then 54, 57,60, until EOF[/B]
 echo "$data[$i] || ";
 } // end if $count

} // end for $i

     } // end if data[0]
 $count++;
} while ($data = fgetcsv($handle,1000,",","'"));
 //  redirect
// header('Location: upload.php?success=1'); die;
} 

[laserlight]

Instead of $c+3 you probably wanted $c += 3.

rulkster2 wrote:

Also, if I don't know the condition ($i<600, $c<1000) ending value, what would be the best to use. Right now I am just using a real high number that I know isn't going to be met.

Wouldn't you know the ending condition because you have read the CSV file into an array of records? Or, if you are reading and processing line by line (i.e., record by record), then the $c += 3 thing is wrong.

[rulkster2]

for ($i = 0; $i < 600; $i++) { 


 for ($i = 48; $i < 600; $c++) {  // or $c+=3
 echo "$data[$i] || ";
 } // end if $count

}

I know why this isn't working. With the second for loop I am still on data[0] and just looping through that a bunch of times. Then data[1] a bunch of times, still on the same record. Just can't figure out what loop to use and where to put. Like I said, rusty!!!!!!!! And I was a noob and still am. 🙂

[laserlight]

Looking at your "full code", I think you are over thinking things. I would expect something like this instead:

$start_from = 48;
if ($_FILES['csv']['size'] > 0) {
    //get the csv file
    $file = $_FILES[csv][tmp_name];
    $handle = fopen($file, 'r');

// Skip the records until the one we start from:
// Note we start counting from 1 as we want the $start_from record.
for ($i = 1; $i < $start_from; $i) {
    fgetcsv($handle, 1000, ',', "'");
}

for ($i = 0; $data = fgetcsv($handle, 1000, ',', "'"); ++$i) {
    if ($i % 3 == 0) {
        print_r($data);
        // or rather, insert the contents of $data to the database
    }
}
// header('Location: upload.php?success=1'); die;
}

If you want to work column by column instead, then you should first read every 3rd record from the 48th into an array (of arrays), then loop over column by column.

[rulkster2]

Thanks, that didn't work.

How can I just tell it, 'Hey give me only record 48, then record 51, then record 54, until you have reached the final record."

[laserlight]

rulkster2 wrote:

Thanks, that didn't work.

Unless I have the motivation to actually test my example, I'm not going to do it since this is not my script. It is up to you to interpret my example for your purposes. So, if you find that incorporating my example into your script still does not work, then you should post exactly what you tried and tell us how does it not work.

rulkster2 wrote:

How can I just tell it, 'Hey give me only record 48, then record 51, then record 54, until you have reached the final record."

That is the logic behind my example. Since you have to retrieve all the records line by line, my idea is to skip the first 47 records by reading and discarding what was read, then read and discard records except for every 3rd record (hence the $i % 3 == 0 test).

By the way, I corrected your $FILES[csv][size] to $FILES['csv']['size']. Likewise, you probably wanted to write $FILES['csv']['tmp_name'] instead of $FILES[csv][tmp_name].

EDIT:
Ah, I spotted a mistake in my first for loop: look carefully at whether the for loop increments $i.

[rulkster2]

First, Thank You for your assistance in this. I am not the best php coder but I am trying to really learn. I took a break, came back and started working with this again.

I did get your script to work, however it is returning every 3rd column instead of every 3rd row(record) and it is returning just one record. I am still playing around with it but I thought I would just post my findings so far.

Thank You again.

[NogDog]

Here's what I'm thinking, FWIW:

$fh = fopen('the_file', 'r');
$counter = 0;
while(($row = fgetcsv($fh, 1000, ',', "'")) !== false)
{
	if(++$counter < 48 or $counter % 3 != 0)
	{
		continue;
	}
	// do stuff with $row
}

[laserlight]

rulkster2 wrote:

I did get your script to work, however it is returning every 3rd column instead of every 3rd row(record) and it is returning just one record. I am still playing around with it but I thought I would just post my findings so far.

What is your current code?

Note that if speed is an issue, I suspect it would be better to just read each line (say with fgets()) and parse with [man]str_getcsv/man only when needed.

NogDog wrote:

Here's what I'm thinking, FWIW:

Essentially the same idea, except that the two loops are simplified into one in exchange for the additional comparisons once past row #48.