"Undefined offset" in PHP array after using explode(...)

Question

Can u tell me why show me tons of notice ?

I am new in php and don't understand where is my mistake, notices from line:

<td>'.$columns[1].'</td>

To line:

$sum+=$columns[2];

Here is my code:

<?php
         if(file_exists('data.txt'))
         {
             $result= file('data.txt');
             $sum='0';

             foreach($result as $value)
             {

                 $columns=explode('-', $value);

                 echo  '<tr>
                             <td>'.$columns[0].'</td>
                             <td>'.$columns[1].'</td>
                             <td>'.$columns[2].'</td>
                             <td>'.$kinds[trim($columns[3])].'</td>
                        </tr>';
                 $sum+=$columns[2];

             }
             echo '<tr>
                <td>--</td>
                <td>--</td>
                <td>' . $sum . ' </td>
                <td>--</td>
            </tr>'; 


         }             
         ?>

I am new in php and don't understand where is my mistake :( notices from line

<td>'.$columns[1].'</td>

to line

$sum+=$columns[2];

Here are the notices:

Notice: Undefined offset: 3 in C:\xampp\htdocs\HomeworkOne\index.php on line 31 
Notice: Undefined index: in C:\xampp\htdocs\HomeworkOne\index.php on line 31
Notice: Undefined offset: 2 in C:\xampp\htdocs\HomeworkOne\index.php on line 33
Notice: Undefined offset: 1 in C:\xampp\htdocs\HomeworkOne\index.php on line 29
Notice: Undefined offset: 2 in C:\xampp\htdocs\HomeworkOne\index.php on line 30
Notice: Undefined offset: 3 in C:\xampp\htdocs\HomeworkOne\index.php on line 31
Notice: Undefined index: in C:\xampp\htdocs\HomeworkOne\index.php on line 31

Notice: Undefined offset: 3 in C:\xampp\htdocs\HomeworkOne\index.php on line 31 Notice: Undefined index: in C:\xampp\htdocs\HomeworkOne\index.php on line 31 Notice: Undefined offset: 2 in C:\xampp\htdocs\HomeworkOne\index.php on line 33 Notice: Undefined offset: 1 in C:\xampp\htdocs\HomeworkOne\index.php on line 29 Notice: Undefined offset: 2 in C:\xampp\htdocs\HomeworkOne\index.php on line 30 Notice: Undefined offset: 3 in C:\xampp\htdocs\HomeworkOne\index.php on line 31 Notice: Undefined index: in C:\xampp\htdocs\HomeworkOne\index.php on line 31 — Tupan, Sep 25 '13 at 12:14
I agree with @FritsvanCampen but my bet is that you're not exploding data correctly. — STT LCU, Sep 25 '13 at 12:14
Notice: Undefined offset: 2 in C:\xampp\htdocs\HomeworkOne\index.php on line 33 Notice: Undefined offset: 1 in C:\xampp\htdocs\HomeworkOne\index.php on line 29 Notice: Undefined offset: 2 in C:\xampp\htdocs\HomeworkOne\index.php on line 30 Notice: Undefined offset: 3 in C:\xampp\htdocs\HomeworkOne\index.php on line 31 Notice: Undefined index: in C:\xampp\htdocs\HomeworkOne\index.php on line 31 Notice: Undefined offset: 2 in C:\xampp\htdocs\HomeworkOne\index.php on line 33 — Tupan, Sep 25 '13 at 12:15
Also, i've retitled your question to match the new informations. Please try to find more meaningful titles in the future — STT LCU, Sep 25 '13 at 12:16
Try to use the condition if(isset($columns[2])) { where ever applicable. — Vineesh, Sep 25 '13 at 12:17
@VineeshPoduval this will throw an undefined offset error too. — Daniel W., Sep 25 '13 at 12:17
@DanFromGermany it won't raise notice, even something like this won't: `isset($undefined_variable[0][5][10][11])`. isset is not a function. — lupatus, Sep 25 '13 at 12:22

score 2 · Answer 1 · edited Jul 02 '16 at 00:16

You are using uninitialized variables. $columns[1], $columns[2] and $columns[3] are not getting values Please try this corrected code:

<?php
if(file_exists('data.txt'))
{
    $result= file('data.txt');
    $sum='0';

    foreach($result as $value)
    {

        $columns=explode('-', $value);
        $kindsDisplay = (isset($columns[3]) && ! empty($kinds[trim($columns[3])])) ? $kinds[trim($columns[3])] : '';
        $one = isset($columns[1]) ? $columns[1] : '';
        $two = isset($columns[2]) ? $columns[2] : '';
        $sum+= isset($columns[2]) ? $columns[2] : 0;

        echo  '<tr>
                   <td>'.$columns[0].'</td>
                   <td>'.$columns[1].'</td>
                   <td>'.$columns[2].'</td>
                   <td>'.$kindsDisplay.'</td>
               </tr>';

    }

    echo '<tr>
              <td>--</td>
              <td>--</td>
              <td>' . $sum . ' </td>
              <td>--</td>
          </tr>'; 

} ?>

score 1 · Answer 2 · answered Sep 25 '13 at 12:17

This is an undefined offset:

$array[0] = "test1";
$array[1] = "test2";

echo $array[3];

You are better off using objects or arrays where you know whats inside.

To get rid use if's:

$array[0] = "test1";
$array[1] = "test2";

if (array_key_exists(3, $array)) {
    echo $array[3];
}

The problem in your case:

$columns = explode('-', $value);

The data you grep from the textfile is not 100% the format you expect, for example:

aaaaa-bbbbbb-cccccc-ddddddd
aaaaa--cccccc-dddddd
aaaaa-ddddd

This means, you need to verify tha data you read is VALID and in the correct format.

score 1 · Answer 3 · edited Feb 14 '14 at 23:03

1

Some things to consider: a blank line at the end of the file could cause this if it only happens once (not each line).

If you want to have default values in case your data is missing seperators you can add

$columns = $columns + array('default_for_key0', 'default1', 'default2', 'default3');

after explode().

edited Feb 14 '14 at 23:03

Eric Leschinski

146,994
96
417
335

answered Sep 25 '13 at 12:23

Christoph Diegelmann

2,004
15
26

score 0 · Answer 4 · answered Sep 25 '13 at 12:19

You read every line of the data file. When you have a blank line you have no data in your $result.

Then you try to explode on an empty string and columns[0] is not set.

Try to check if the array is not empty perhaps with

if(count($columns) > 2) {

}

or check wheather the array is set.

if(isset($columns[0])) {

}

otherwise you can fill the array with default data.

score 0 · Answer 5 · answered Sep 25 '13 at 12:19

Your data is probably not as sane as you think.

$columns=explode('-', "abc");
$columns[0]; // "abc";
$columns[1]; // gives: Undefined offset 1

Either ensure your data is what you expect, or explicitly try to find error cases, like a line with no -.

You can do count($columns) to find out how many columns there are.

Be very wary of constructions like:

$kinds[trim($columns[3])]

You have 2 possible undefined offsets here. $columns[3] and $kinds[#index#] can both be undefined.

score 0 · Answer 6 · answered Sep 25 '13 at 12:39

Try this way and you will see if you have 4 columns every time:

<?php
if (file_exists('data.txt')) {
    $result= file('data.txt');
    $sum=0;

    foreach($result as $value) {
        $columns=explode('-', $value);
        echo  '<tr>';
        foreach ($columns as $key => $column) {
            echo '<td>'.$column.'</td>';
            if ($key == 2) $sum += $column;
        }
    echo '</tr>';
    echo '<tr><td>--</td><td>--</td><td>'.$sum.'</td><td>--</td></tr>'; 
}             
?>

score 0 · Answer 7 · answered Sep 25 '13 at 13:20

First you will need to set $kinds as array. Secondly, check array keys before you use in the program else it will throw errors like below: http://d.pr/i/GzVk

Check the revised code, I Hope this will helpful for you.

<?php
if(file_exists('data.txt'))
{
$result= file('data.txt');
$sum='0';
$kinds = array();

foreach($result as $value)
{

$columns=explode('-', $value);

if(array_key_exists($columns[0], $columns)) {
echo '<td>'.$columns[0].'</td>';
}
if(isset($columns[1]) && array_key_exists($columns[1], $columns)) {
echo '<td>'.$columns[1].'</td>';
}

if(isset($columns[2]) && array_key_exists($columns[2], $columns)) {
echo '<td>'.$columns[2].'</td>';
$sum+=$columns[2];
}

if(isset($columns[3]) && array_key_exists($columns[3], $columns)) {
echo '<td>'.$kinds[trim($columns[3])].'</td>';
}

echo      '</tr>';


}
echo '<tr>
<td>--</td>
<td>--</td>
<td>' . $sum . ' </td>
<td>--</td>
</tr>';


}
?>

"Undefined offset" in PHP array after using explode(...)

7 Answers7