PHP的do-while循环不起作用

Question

So I've been stuck on this do-while loop not working for about two hours. I really don't understand why it doesn't work. I'm getting this error:

Notice: Undefined offset: 9 in /public_html/me/yes.php on line 60

The only problem I think of is that it doesn't accept while loops in a do-while.

Here is my working code for just the inner while loop:

$maxcols = $numofcols-1; //=9
$maxrow = count($myarray)-1; //=44
$currentcol=0;
    $currentrow=1;
    //do {
    $collection->insert(array($title[$currentcol] => $myarray[$currentrow][$currentcol]));
    $currentcol++;
    while ($currentcol<=$maxcols){
    $newdata = array('$set' => array($title[$currentcol] => $myarray[$currentrow][$currentcol]));
    $currentcol--;
    $collection->update(array($title[$currentcol] => $myarray[$currentrow][$currentcol]), $newdata);
    $currentcol++;
    $currentcol++;

    }
    $currentrow++;

    //} while ($currentrow<=$maxrow);

If I uncomment the two line's "//do {" and "//} while ($currentrow<=$maxrow);" my program dies with the error I mentioned above. Is there something dead simple as to why it's breaking my code? Thanks in advance

UPDATE:

Line 60 is:

$collection->insert(array($title[$currentcol] => $myarray[$currentrow][$currentcol]));

Answer 1

The inner while loop ends with $currentcol set to $maxcols . The next time you get there $currentcol has been increased by one (in the previous line) so it's $maxcols+1 , so the while loop doesn't run. The next loop in the outer do loop now tries to access $title[ $maxcols+1 ] which is undefined.

Answer 2

$currentrow is initialized to the value 1 . If your array only contains one element, this has index 0 , so you're getting an "index out of bounds" error.

Also, you're determining the number of columns once globally (outside the while loop for the rows). Maybe you should determine the number of columns for each row just before you loop over the columns.

Also, you're not resetting the column index variable to 0, you just keep incrementing. Which causes an error in the second row, as you're starting out with a column index that doesn't exist.

Suspecting that PHP does not allow a while loop within a while loop is nonsense. Nested loops are a used very frequently - you just have to get the condition right

Answer 3

Try this :

$maxcols = $numofcols-1; //=9
$maxrow = count($myarray)-1; //=44
$currentcol=0;
$currentrow=1;
do {
    if ($currentcol<9)
    {
         $collection->insert(array($title[$currentcol] => $myarray[$currentrow][$currentcol]));
         $currentcol++;
         while ($currentcol<=$maxcols){
             $newdata = array('$set' => array($title[$currentcol] => $myarray[$currentrow][$currentcol]));
             $currentcol--;
             $collection->update(array($title[$currentcol] => $myarray[$currentrow][$currentcol]), $newdata);
             $currentcol++;
             $currentcol++;
         }
         $currentrow++;
    }

} while ($currentrow<=$maxrow);

Answer 4

The answer:

Such a simple little mistake, but there was no reset on the $currentcol

Moving the initialization down right below the do statement made it work correctly.Can you tell it's getting late? hahaha Thanks all.

$currentrow=1;

do {
$currentcol=0;

$collection->insert(array($title[$currentcol] => $myarray[$currentrow][$currentcol]));
$currentcol++;
while ($currentcol<=$maxcols){
$newdata = array('$set' => array($title[$currentcol] => $myarray[$currentrow][$currentcol]));
$currentcol--;
$collection->update(array($title[$currentcol] => $myarray[$currentrow][$currentcol]), $newdata);
$currentcol++;
$currentcol++;

}
$currentrow++;

} while ($currentrow<=$maxrow);