通过php中的数组循环

Question

<?php
for($i=0; $i<sizeof($top_name); $i++)
{
  for($i=0; $i<sizeof($top_name); $i++)
  {
    echo "<tr><td>".$sub_name[$i]."</td><td>".$sub_diff[$i]."</td></tr>";
    echo "<tr><td>".$top_name[$i]."</td><td>".$top_diff[$i]."</td>  <td>".$top_size[$i]."</td></tr>";
  }
}

?> 

Error :

Notice: Undefined offset: 2 in C:\xampp\htdocs\TRY\data.php on line 28
Notice: Undefined offset: 2 in C:\xampp\htdocs\TRY\data.php on line 28

I'm trying to fetch arrays and arranging them in table but it is giving that error.

Please solve this. Thanks in advance...

Answer 1

Assuming you have these elements in $top_name and $sub_name array:

$top_name = array( 'First Name', 'Second Name', 'Third Name', 'Fourth Name' );
$sub_name = array( 'Sub One', 'Sub Two' );

your two loops acts in this way:

1) main loop    > $i = 0 > executed
2)     2nd loop > $i = 0 > executed
3)     2nd loop > $i = 1 > executed
4)     2nd loop > $i = 2 > executed > undefined offset for $sub_name
5)     2nd loop > $i = 3 > executed > undefined offset for $sub_name
6) main loop    > $i = 4 > not executed

So, the deeper loop is executed also for non-existent $sub_name elements, whereas the main loop is executed only once.

In the second loop, you have to change incrementing variable name and condition variable:

for( $i=0; $i<sizeof( $top_name ); $i++ )
{
    for( $n=0; $n<sizeof( $sub_name ); $n++ )
    {
        echo "<tr><td>".$sub_name[$n]."</td><td>".$sub_diff[$n]."</td></tr>";
        echo "<tr><td>".$top_name[$i]."</td><td>".$top_diff[$i]."</td>  <td>".$top_size[$i]."</td></tr>";
    }
}