PHP arrays in a loop not clearing

Question

I am writing a utility to do some data loading from text files. I have a collection of dictionary files that i am processing into arrays that define the structure of the data files. Yes, i could use classes or otherwise, but using arrays, i have been stumped.

Let's say i have 3 files that i read and load into arrays. When i read the arrays, the 3rd instance has elements of the second despite trying to use unset and other things. What am I missing? I am on cygwin using php 5.3.16

Following are examples of list, but not the real lists. so, please disregard the substr statements as they are not real

fname c 1 16
lname c 17 30

addr c 1 20
city c 21 30
state c 31 40
zip n 41 45

bday d 1 9
ssn c 10 18

when loading with the code below, the 3rd array has elements from the second, namely bday, ssn, state and zip.

$cnt = 0;
while ($s = fgets($fp, 1024)) {
    $fldprops = array();
    $fldprops[0] = trim(substr($s,0,8));
    $fldprops[1] = trim(substr($s,9,1));
    $fldprops[2] = trim(substr($s,11,3));
    $fldprops[3] = trim(substr($s,15,3));
    $flds[$cnt] = $fldprops;
    $cnt++;
    unset($fldprops);
}

I had thought either one of $fldprops = array(); or unset() would clear the array but it is not working.

Update: I mistook the point of failure. it is not apparently at writing to the outer array, but in reading. As i mentioned in a comment, later in the code, i have a foreach loop and here it is failing:

foreach ($flds as $fldprop) {
     var_dump($fldprop);
}

here, i get bday, ssn, state and zip (the last two entries of the second array merged with the 3rd array).

$fldprops = array() creates a new empty array, so how do you determine that it's not working? — Ja͢ck
– Ja͢ck, Commented Oct 5, 2012 at 15:19
Can you please rephrase the question. I have a hard time understanding what you are trying to do and where it goes wrong. — Gordon
– Gordon, Commented Oct 5, 2012 at 15:19
It's because you forgot the vowels in the word field. I'm sure that's it. — SeanCannon
– SeanCannon, Commented Oct 5, 2012 at 15:21

Praveen Kumar Purushothaman · Accepted Answer · 2012-10-05 15:19:06Z

1

This is the output I am getting:

<?php
    $flds = array();
    $cnt = 0;
    $s = "HelloWorldNiceToSeeYou";
    $fldprops = array();
    $fldprops[0] = trim(substr($s,0,8));
    $fldprops[1] = trim(substr($s,9,1));
    $fldprops[2] = trim(substr($s,11,3));
    $fldprops[3] = trim(substr($s,15,3));
    $flds[$cnt] = $fldprops;
    $cnt++;
    unset($fldprops);
    var_dump($flds, $cnt, $fldprops);
?>

Output:

<br />
<b>Notice</b>:  Undefined variable: fldprops in <b>/code/MQpnac</b> on line <b>13</b><br />
array(1) {
  [0]=>
  array(4) {
    [0]=>
    string(8) "HelloWor"
    [1]=>
    string(1) "d"
    [2]=>
    string(3) "ice"
    [3]=>
    string(3) "oSe"
  }
}
int(1)
NULL

PHP Notice:  Undefined variable: fldprops in /code/MQpnac on line 13

So PHP is doing it right. Check out live at: http://codepad.viper-7.com/MQpnac

answered Oct 5, 2012 at 15:19

Praveen Kumar Purushothaman

167k27 gold badges215 silver badges261 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Cord Over a year ago

Thank you - turns out i wasn't testing the failure in the right place. In creating the array and assigning it to the outer array, the values are fine. the issue, as @Jack points out is in the use. So, later in the code, i have this: foreach($arr as $arrelem) and when i hit the 3rd one, i am getting old references to the previous entry.

Cord Over a year ago

Praveen, do you have any insight into why in my using a foreach loop, i am somehow getting references to elements in earlier arrays. See my update above - i did a var_dump on the creation side and things seem find, but then a var_dump in the midst of the foreach loop and in the 3rd iteration, i see properties from the 2nd nested array. thanks.

Cord Over a year ago

Nevermind - stupid inner/outer loop issue... thanks for your help.

RobMasters · Accepted Answer · 2012-10-05 15:27:40Z

0

Why even bother with the temporary variable?

$cnt = 0;
while ($s = fgets($fp, 1024)) {
    $flds[$cnt] = array(
        trim(substr($s,0,8)), 
        trim(substr($s,9,1)), 
        trim(substr($s,11,3)), 
        trim(substr($s,15,3)), 
    )
    $cnt++;
}

answered Oct 5, 2012 at 15:27

RobMasters

4,1462 gold badges29 silver badges34 bronze badges

2 Comments

Cord Over a year ago

This is helpful, but not a solution to my problem. Thanks.

RobMasters Over a year ago

No worries, I must have misunderstood the problem. I still don't think I understand what the problem was, but it sounds as though Praveen Kumar has sorted it anyway for you. So you should click on the tick next to his answer to mark it as accepted.

Collectives™ on Stack Overflow

PHP arrays in a loop not clearing

2 Answers 2

Output:

So PHP is doing it right. Check out live at: http://codepad.viper-7.com/MQpnac

3 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Output:

So PHP is doing it right. Check out live at: http://codepad.viper-7.com/MQpnac

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related