Adding one character to each array key in PHP [duplicate]

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Possible Duplicate:

Fastest way to add prefix to array keys?

I had a quick question about arrays in PHP. I need to add a couple of characters to each key i开发者_StackOverflown an array, for instance:

name => Mark age => 23 weight = > 150

needs to be converted to:

r_name => Mark r_age => 23 r_weight => 150

Any help would be appreciated, thanks.

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Iterate the array, add a new item with the modified key and delete the original item:

foreach ($arr as $key => $val) {
    $arr['r_'.$key] = $val;
    unset($arr[$key]);
}

As foreach works with an internal copy of the array, you won’t run into an infinite loop.

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Take a look at this post: In PHP, how do you change the key of an array element?

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If you can be sure, that there are no two keys $K1,$K2 in your array with $K1 = "r_".$K2 , you can use the solution given by Gumbo - its efficient and nice.

If you can not guarantee the stated condition, i would prefer generating a new array with the altered keys and deleting/overwriting the old one afterwards. This is not as memory efficient as the other solution but wont fail.

Another thing to keep in mind is, that unset is a bit slow in PHP. So Unsetting a lot of elements in your array might be slower than working with a copy and deleting the original afterwards.