00 Votes

Print current and next Value of Array - Undefined Array Key Error

Question by Guest | 2022-07-30 at 12:16

I have the following PHP code:

$var = array(2, 5);
$cnt = count($var);

for ($i = 0; $i < $cnt; $i++) {
   echo $var[$i]."\n";
   echo $var[$i+1]."\n";
}

However, the code shows this error:

(!) Warning: Undefined array key 2 in 
C:\xampp\htdocs\CAYTASOURCE\snippets\q.php on line 7

I want to print the current and next array value.

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-11 Vote

The problem with your code is as follows: You have an array with two elements (indexes 0 and 1). Then you loop through this array with $i < number of array elements. That means in the loop, $i takes the values 0 and 1. This is no problem for $var[$i] (0 and 1 are in the array range), but for $var[$i+1] (1 in but 2 not in the array range).

So, you have to possibilities:

for ($i = 0; $i < $cnt - 1; $i++) {
   echo $var[$i]."\n";
   echo $var[$i+1]."\n";
}

Here we use $cnt - 1 so that also $var[$i+1] has no change to get out of the index range of the array.

Or we can go like that:

for ($i = 0; $i < $cnt; $i++) {
   echo $var[$i]."\n";
}

Here we are using no $i+1 so that we are again always in the index range also without $cnt - 1.
2022-07-30 at 16:48

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