Execute function on every value of a key - php

Question

I have an array with the following structure :
$array = array(
array("animal" => "dog","color" => "black"),
array("animal" => "cat","color" => "white"),
array("animal" => "mouse","color" => "grey")
);
Now I need to execute a function on every value of animal, say make the values uppercase. This is the expected output :
array(3) {
[0]=>
array(2) {
["animal"]=>
string(3) "DOG"
["color"]=>
string(5) "black"
}
[1]=>
array(2) {
["animal"]=>
string(3) "CAT"
["color"]=>
string(5) "white"
}
[2]=>
array(2) {
["animal"]=>
string(5) "MOUSE"
["color"]=>
string(4) "grey"
}
}
When I do
for (int i=0; i<=$array.size(); i++) {
$array["animal"] = array_map('strtoupper', $array["animal"]);
}
I get this error:
<b>Parse error</b>: syntax error, unexpected 'i' (T_STRING), expecting ';' in <b>[...][...]</b> on line <b>15</b><br />

Answer 1

You can achieve this using following ways:
<?php
$array = array(
array("animal"=>"dog","color"=>"black"),
array("animal"=>"cat","color"=>"white"),
array("animal"=>"mouse","color"=>"grey")
);
foreach ($array as $key => $value) {
foreach ($value as $key1 => $value1) {
if($key1 == 'animal'){
$keys = ucfirst($value1);
$array[$key][$key1]=$keys;
}
}
}
echo "<pre>";print_r($array);
?>

Answer 2

You can also use array_walk Function of PHP
array_walk
$array = array(
array("animal"=>"dog","color"=>"black"),
array("animal"=>"cat","color"=>"white"),
array("animal"=>"mouse","color"=>"grey")
);
$array_map = array_walk($array, 'walk_array');
function walk_array(&$item, $key){
$item['animal'] = strtoupper($item['animal']);
}
echo '<pre>';
print_r($array);

Answer 3

Solution
You could use a for() loop to iterate through you animals. You'll have to count the number of animals you got first with the count() function cast to a variable. Then, you'll be able to make uppercase on your animal index with the strtoupper() function. Also note that you can use the new PHP syntax for arrays like so [] which is a quicker way to do it.
Source-code
<?php
$animals = [
[
'animal' => 'dog',
'color' => 'black'
],
[
'animal' => 'cat',
'color' => 'white'
],
[
'animal' => 'mouse',
'color' => 'grey'
]
];
for ($i = 0; $i < count($animals); $i++)
{
$animals[$i]['animal'] = strtoupper($animals[$i]['animal']);
}
echo '<pre>';
print_r($animals);
echo '</pre>';
Result
Array
(
[0] => Array
(
[animal] => DOG
[color] => black
)
[1] => Array
(
[animal] => CAT
[color] => white
)
[2] => Array
(
[animal] => MOUSE
[color] => grey
)
)
Demo.
PHP : for loop.
PHP : count().
PHP : strtoupper().
PHP : arrays.