[SOLVED] limiting loop question

[dennismonsewicz]

I have been doing a lot of studying up on loops here lately, hence the reason for all of my loop questions, and I am stuck on a particular script I am trying to finish.

 

code:

while($results = mysql_fetch_assoc($structure)) {
	echo '<td>';
	      echo $results['Field'];
	echo '</td>';

$array[] = $results['Field'];
}

 

How would I go about limiting the number of fields that show up?

 

Here is the SQL query I am using to pull the fields:

$tableName = mysql_real_escape_string($_GET['tablename']);
$structure = mysql_query("DESCRIBE " . $tableName)or die(mysql_error());

[.josh]

$limit = 10;
for ($x = 0;$x < $limit; $x++) {
  $results = mysql_fetch_assoc($structure);
      echo '<td>';
            echo $results['Field'];
      echo '</td>';
                              
   $array[] = $results['Field'];
}

[dennismonsewicz]

sweet Thanks!!!!!

[knsito]

better to keep a counter and use break

http://us2.php.net/manual/en/control-structures.break.php

This will exit the current level of the loop

 

$i=0;

while($result=mysql_fecth....){

  $i++;

  if($i==10)

  break;

}

 

While you are learning take a look at continue as well

http://us2.php.net/manual/en/control-structures.continue.php

[.josh]

So...how is that better?  Way I see it, your method is technically less efficient, as it runs 2 conditions every iteration.

[knsito]

So...how is that better?  Way I see it, your method is technically less efficient, as it runs 2 conditions every iteration.

 

Your method will result in undesireable results.

If the number of rows you get back from the table is less than 10 you are echoing empty cells and adding Nulls into your array.

 

Besides the OP said he was trying to learn, why not point him to useful constructs such as break and continue, since for loops are a dime a dozen

 

[.josh]

So...how is that better?  Way I see it, your method is technically less efficient, as it runs 2 conditions every iteration.

 

Your method will result in undesireable results.

If the number of rows you get back from the table is less than 10 you are echoing empty cells and adding Nulls into your array.

 

Umm..the same can be said about your method.

 

[knsito]

Umm..the same can be said about your method.

 

eh?

 

<?php
$structure = array(1,2,3,4,false); //imitating the data from mysql_fetch_assoc
/* http://us2.php.net/manual/en/function.mysql-fetch-assoc.php */

$limit = 10;
for ($x = 0;$x < $limit; $x++) {
  $array[] = $structure[$x];
}
var_dump($array);

/* ================= */

unset($array);
$i=0;
while($result=$structure[$i]){
$array[] = $result;
$i++;
if($i==10)
	break;
}
var_dump($array);
?>

[dennismonsewicz]

ok so I am trying the second opinion on this loop stuff and here is my code:

 

$i = 0;
							  while($results = mysql_fetch_assoc($structure)) {
								$i++
								if($i == 10) {
									 echo '<td>';
								            echo $results['Field'];
								      echo '</td>';

								   $array[] = $results['Field'];
									break;
								}
							}

 

I now get a blank page

[knsito]

Hi

 

You want to put

echo '<td>';
echo $results['Field'];
echo '</td>';
$array[] = $results['Field'];

 

Before your if statment, you only need the break; in there. This will exit your while loop when 10 is reached

if($i == 10) { 
   break;
}

 

ok so I am trying the second opinion on this loop stuff and here is my code:

 

$i = 0;
							  while($results = mysql_fetch_assoc($structure)) {
								$i++
								if($i == 10) {
									 echo '<td>';
								            echo $results['Field'];
								      echo '</td>';

								   $array[] = $results['Field'];
									break;
								}
							}

 

I now get a blank page

[dennismonsewicz]

sweet! it works now! I also had forgot to place a semicolon after the $i++ but thanks for EVERYONE'S help!!!