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up vote 5 down vote favorite

I have a pretty basic question but I am stuck. I am pretty new to php and I have an array like this:

$array = array(
    'one' => 1,
    'two' => array('key1' => 'val1','key2' => 'val2'),
    'three' => array('key1' => 'val1','key2' => 'val2'),
    'four' => array('key1' => 'val1','key2' => 'val2')
);

and for each of the arrays in the array (that is, 'two, 'three', and 'four'), I want to insert 'key3' => 'val3' into those arrays.

I tried this:

foreach($array as $item) {
    if (gettype($item) == "array") {
        $item['key3'] = 'val3';
    }
}

But it doesn't work, and I'm not sure why. Using various print_r's all over the place, it seems to insert 'key3' => 'val3' into $item if I print it out in the loop, but the original array seems unchanged. I also tried a regular for loop but that didn't work either.

share|improve this question
    
Do the key and its value are equals for each sub-array? –  sємsєм May 10 '13 at 22:58

2 Answers 2

up vote 10 down vote accepted

foreach works with a copy of $item, so you cannot modify your original array inside the foreach. One way to work around this is to use the & operator.

foreach($array as &$item) {
    if (is_array($item)) {
        $item['key3'] = 'val3';
    }
}

Another, more elegant way would be to use array_walk():

array_walk($array, function (&$v, $k) { 
    if (is_array($v)) {
        $v['key3'] = 'val3';
    }
});

This example will work from PHP 5.3, where Closures were introduced.

share|improve this answer
    
$item is only generated for the loop . You mean &$array['key3'] = 'val3'; ! –  moskito-x May 10 '13 at 23:55
    
@moskito-x I certainly mean what I wrote. That's the point of it. Check the foreach manual page I linked. –  kapa May 10 '13 at 23:59
    
To change $item is useless. Will be always overwritten by the next loop. –  moskito-x May 11 '13 at 0:01
    
@moskito-x codepad.org/GxZbQ1bD –  kapa May 11 '13 at 0:03
2  
But As foreach relies on the internal array pointer changing it within the loop may lead to unexpected behavior. therefore you have to unset the reference . unset($item); // break the reference with the last element. structures.foreach –  moskito-x May 11 '13 at 0:21
up vote 0 down vote

PHP has a function to check whether a variable is an array or not: is_array(). Use this:

if (is_array($item)) { ...
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