CODEWITHSUNDEEP
phparrays
zen
zen

Reputation: 1165

PHP's array_flip causes undefined offset

This is my original array:

Array ( [0] => pid [1] => pname [2] => paddress [3] => pphone)

After using array_flip, it becomes this, which is how I want it:

Array ( [pid] => 0 [pname] => 1 [paddress] => 2 [pphone] => 3)

However, I can't seem to use the array anymore. When I try to loop through each item, I get undefined offset.

Upvotes: 2

Views: 191

Answers (3)

Richard Christensen
Richard Christensen

Reputation: 2166

if you were using a for loop before you flipped the array it will no longer work because the array becomes an associative array. You can use a foreach($array as $k => $v ) loop and it should work.

for loops only work with an array that is indexed numerically.

for($i=0;$i<count($array);$i++)
{
  echo $array[$i];
}

foreach is used for associative arrays.

foreach($array as $k => $v)
{
  echo $k.'=>'.$v;
}

Edit: you can use a foreach array with a numerically indexed array as well.

Upvotes: 1

DarkMantis
DarkMantis

Reputation: 1516

Sure, if you are trying to access it by a string-key then it will throw the error 'undefined offset x'.

You need to ensure that if you are running it through a loop then you need to specify the key and value:

foreach($array as $key => $value){
    // do stuff
}

Or if you prefer you can get the values/keys without doing a loop, which is probably more efficient way of doing it:

$keys = array_keys($array);
$values = array_values($array);

$x = array_flip($array);
$flipped_keys = array_keys($x);
$flipped_values = array_values($x);
echo $x[$flipped_keys[0]];

Hopefully this will help

Upvotes: 0

user2092317
user2092317

Reputation: 3338

use foreach to loop the array

 foreach($array as $key => $value){
    echo "key=$key"."</br>";
    echo "value=$value";
    }

Upvotes: 0

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