Strange behavior in foreach loop over multidimensional array

Question

THE QUESTION

Why is the line with "l++;" impacting the loop counts of the foreach loop? That line is merely there as a counter but somehow it is impacting the end result.

Can someone please help explain what is going on here?

THE CODE

I have the following multidimensional array:

$team_array = array(
    array(68, 6, 0, 10, "1.000"),
    array(72, 6, 0, 10, "1.000"),
    array(65, 6, 0, 8, "1.000"),
    array(62, 6, 0, 4, "1.000"),
    array(54, 3, 3, 3, ".500"),
    array(55, 3, 3, -5, ".500"),
    array(59, 0, 6, -16, ".000")
);

I am using the following code to loop over the arrays.

$foo = "1.000";    
$k = 0;
$l = 0;
$m = 0;
$n = 0;
foreach($team_array as $index => $inner_arr)
{
    foreach($inner_arr as $value)
    //echo $value.", ";
    //echo "<br/>";
    $l++;
    { 
        $m++;
        echo "index - $index<br>";
        echo "perc = ".$team_array[$index][4]."<br>";
        if ($team_array[$index][4] == $foo)
        {
            $tie_tm[] = $team_array[$index][0];
            $n++;
        }   

    }

    $k++;
}
echo "k - $k<br>";
echo "l - $l<br>";
echo "m - $m<br>";
echo "n - $n<br>";

echo "<pre>";
print_r($tie_tm);

I have left the debugging bits in as they show the strange (to me) behavior. Specifically, if I comment out the line "l++;" I get LOTS more loops than I would expect. Running this code without the "l++;" line give me this:

k - 7
l - 0
m - 35
n - 20
Array
(
[0] => 68
[1] => 68
[2] => 68
[3] => 68
[4] => 68
[5] => 72
[6] => 72
[7] => 72
[8] => 72
[9] => 72
[10] => 65
[11] => 65
[12] => 65
[13] => 65
[14] => 65
[15] => 62
[16] => 62
[17] => 62
[18] => 62
[19] => 62
)

With it left in, I get:

k - 7
l - 35
m - 7
n - 4
Array
(
[0] => 68
[1] => 72
[2] => 65
[3] => 62
)

This is the result I want and expected.

In the end, what I need is exactly what I am getting in the final result with 4 elements in the array. I would like to remove the debugging bits but need to understand how I might need to alter this code to keep my end result.

Thanks in advance!

foreach($inner_arr as $value) $l++; { ... } this is almost certainly a typo. You probably meant foreach($inner_arr as $value) { $l++; ... } — p.s.w.g
– p.s.w.g, Commented Apr 27, 2014 at 16:06

Parag Tyagi · Accepted Answer · 2014-04-27 16:11:59Z

1

Reframed your code a bit. Try -

$team_array = array(
        array(68, 6, 0, 10, "1.000"),
        array(72, 6, 0, 10, "1.000"),
        array(65, 6, 0, 8, "1.000"),
        array(62, 6, 0, 4, "1.000"),
        array(54, 3, 3, 3, ".500"),
        array(55, 3, 3, -5, ".500"),
        array(59, 0, 6, -16, ".000")
      );

$result = array();
for($i=0; $i<4; $i++)
{
    $result[] = $team_array[$i][0];
}

print_r($result);

OUTPUT

Array
(
   [0] => 68
   [1] => 72
   [2] => 65
   [3] => 62
)

DEMO

http://3v4l.org/RJu69#v430

answered Apr 27, 2014 at 16:11

Parag Tyagi

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2 Comments

AD7six Over a year ago

You don't explain the problem with the existing code, which is "the question" and probably, in this instance, more useful to the OP.

Parag Tyagi Over a year ago

Yes I know. Still thought that too much of OP's code is not useful, since it can be done in one simple for loop

sfletche · Accepted Answer · 2014-04-27 16:07:28Z

1

Remove the code between your foreach header and the opening curly brace.

What you've inadvertently done is create a foreach loop that actually works like this

foreach($inner_arr as $value) 
    $l++;

When what you want is a foreach loop that looks like this

foreach($inner arr as $value) {
    // all your looping code should go in between the curly braces 
    // and the curly braces need to immediately follow the foreach header (with nothing in between)
}

answered Apr 27, 2014 at 16:07

sfletche

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Comments

nl-x · Accepted Answer · 2014-04-27 16:15:45Z

1

You have put l++ between your second foreach and its corresponding {}. So in stead of foreaching your code between the {}, you are only foreaching the l++. Try placing your l++ before the second foreach or inside the corresponding {}.

edited Apr 27, 2014 at 16:15

answered Apr 27, 2014 at 16:08

nl-x

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Comments

MIrlynn · Accepted Answer · 2014-04-27 16:20:23Z

Thanks for the quick feedback. I really appreciate it!!!

The answers helped me realize that the inner foreach loop was really doing nothing for me. I am only interested in looking in a single designated dimension of the multidimensional array and was getting my desired result without the use of the inner foreach loop.

I modified the code as follows:

$foo = "1.000";
$m = 0;
$n = 0;
foreach($team_array as $index => $inner_arr)
{
    $m++;
    echo "index - $index<br>";
    echo "perc = ".$team_array[$index][4]."<br>";
    if ($team_array[$index][4] == $foo)
    {
        $tie_tm[] = $team_array[$index][0];
        $n++;
     }   
}

echo "m - $m<br>";
echo "n - $n<br>";


echo "<pre>";
print_r($tie_tm);

Again... thanks for all the feedback. This community is incredible!

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