Get the index value of an array in php

Question

I have an array:

$list = array('string1', 'string2', 'string3');

I want to get the index for a given value (i.e. 1 for string2 and 2 for string3)

All I want is the position of the strings in the array

• string1 is 0
• string2 is 1
• string3 is 2

How to get this? I tried array_search but it was no use

Answer 1

Probably the easiest way is to just use a for loop, and return the loop counter when you find the string you are looking for.

Answer 2

Try the array_keys PHP function.

$key_string1 = array_keys($list, 'string1');

Answer 3

array_search is the way to do it.

From the docs:

$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');

$key = array_search('green', $array); // $key = 2;
$key = array_search('red', $array);   // $key = 1;

You could loop over the array manually and find the index but why do it when there's a function for that. This function always returns a key and it will work well with associative and normal arrays.

Answer 4

array_search should work fine, just tested this and it returns the keys as expected:

$list = array('string1', 'string2', 'string3');
echo "Key = ".array_search('string1', $list);
echo " Key = ".array_search('string2', $list);
echo " Key = ".array_search('string3', $list);

Or for the index, you could use

$list = array('string1', 'string2', 'string3');
echo "Index = ".array_search('string1', array_merge($list));
echo " Index = ".array_search('string2', array_merge($list));
echo " Index = ".array_search('string3', array_merge($list));

Answer 5

If you're only doing a few of them (and/or the array size is large), then you were on the right track with array_search:

$list = array('string1', 'string2', 'string3');
$k = array_search('string2', $list); //$k = 1;

If you want all (or a lot of them), a loop will prob do you better:

foreach ($list as $key => $value) {
    echo $value . " in " . $key . ", ";
}
// Prints "string1 in 0, string2 in 1, string3 in 2, "

Answer 6

Could you be a little more specific?

$key = array_search('string2',$list)

works fine for me. Are you trying to accomplish something more complex?

Answer 7

Other folks have suggested array_search() which gives the key of the array element where the value is found. You can ensure that the array keys are contiguous integers by using array_values():

$list = array(0=>'string1', 'foo'=>'string2', 42=>'string3');
$index = array_search('string2', array_values($list));
print "$index\n";

// result: 1

You said in your question that array_search() was no use. Can you explain why? What did you try and how did it not meet your needs?

Answer 8

Sorry, the array i use is a "multi-dimensional" array of the form

$array = array(
'string1' => array('a' => '', 'b' => , 'c' => ''),
'string2' => array('a' => '', 'b' => , 'c' => ''),
'string3' => array('a' => '', 'b' => , 'c' => ''),
);

array_search() does not work for multidimensional arrays (i tried for this) So i preferred using foreach and incrementation

my solved code is

function find_array_index($to_find_Key = '', $in_Array = ''){
    $index = 0;
    foreach ($in_Array as $key => $value) {
        if($key == $to_find_Key){
            return $index;
        }
        $index++;
    }
}

using find_array_index('string2', $array); gave me the result 1

Anyway thanks all for your support !

Answer 9

This code should do the same as your new routine, working with the correct multi-dimensional array..

 $arr = array(
  'string1' => array('a' => '', 'b' => '', 'c' => ''),
  'string2' => array('a' => '', 'b' => '', 'c' => ''),
  'string3' => array('a' => '', 'b' => '', 'c' => '')
 );

 echo 'Index of "string2" = '. array_search('string2', array_keys($arr));