How does this loop work even though counter isnt used? - php

Question

i am exploring some old php files for the nostalgia, and i noticed this is what ive written before to fetch some records:
<?php
for ( $counter = 0; $row = mysqli_fetch_row( $result );++$counter )
{
print( "<tr>" );
foreach ( $row as $key => $value )
{
if($key == '6')
{
if($value == '1'){print( "<td>12/9/15 6:00PM - 7:00PM</td>" );}
if($value == '2'){print( "<td>12/9/15 7:00PM - 8:00PM</td>" );}
if($value == '3'){print( "<td>12/9/15 8:00PM - 9:00PM</td>" );}
if($value == '4'){print( "<td>12/10/15 6:00PM - 7:00PM</td>" );}
if($value == '5'){print( "<td>12/10/15 7:00PM - 8:00PM</td>" );}
if($value == '6'){print( "<td>12/10/15 8:00PM - 9:00PM</td>" );}
}
else
{
print( "<td>$value</td>" );
}
}
print( "</tr>" );
}
mysqli_close( $database );
?>
i changed it to while ($row = mysqli_fetch_row( $result )) and it works as well, as expected. i am just trying to understand the logic behidn how the for loop method works when $counter isnt being used...
i am scrambling to understand why i used this kind of logic, and how is it even working when $counter isnt even used for indexing or anything.

Answer 1

Easiest way to understand how this is working is by dissecting the for loop.
for (<initialization>; <condition>; <update expresion>)
In your case you have a counter that is being set initially, and incremented.
for ( $counter = 0; $row = mysqli_fetch_row( $result );++$counter )
You aren't using the counter, but it actually doesn't matter since the only thing that determines if the loop continues is if the condition is true. Since eventually mysqli_fetch_row stops returning results, the loop will terminate. The $counter variable is unused and ignored for the purpose of the loop.
You could also rewrite your for loop to look like:
for (;$row = mysqli_fetch_row( $result );) and this would also work the same. But then, what is a while loop? It's just a for loop without an initialization and update expression. Thus you could rewrite this again as:
while ($row = mysqli_fetch_row( $result ))
I hope this clears things up.