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Difference between array,list and map

Posted on 2011-09-27
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HI Experts,

I want to know the difference between arrays,list and map and when is best to use them.

Thanks.
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Question by:dvcphp
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Expert Comment

by:Lukasz Chmielewski
ID: 36712414
The difference between array and list is that you can use array with keys which are not varibles, list assigns the array values to list vars, array_map applies the function to the array elements. Take a look at the examples at manual pages:

http://pl2.php.net/manual/en/function.array.php
http://www.php.net/manual/en/function.list.php
http://php.net/manual/en/function.array-map.php
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Author Comment

by:dvcphp
ID: 36712467
Thanks Genius but I am still confused as to when to use one over the other.
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Expert Comment

by:Lukasz Chmielewski
ID: 36712516
The most cases - you use array, basicaly it depends on what you want to do.
Let's make examples:

<?php

// lets's make an array
$a = array(1, 2, 3);

// show me the array
print_r($a);

// let's make a list
list($first, $second, $third) = $a;

// list is like an array keys, but you can acces them with 
// variable name like $first, not with $a[0]
echo $first;

?>

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Expert Comment

by:Lukasz Chmielewski
ID: 36712525
Or more complete one:

<?php


function addone($n)
{
    return($n + 1);
}



// lets's make an array
$a = array(1, 2, 3);

// show me the array
print_r($a);

// let's make a list
list($first, $second, $third) = $a;

// list is like an array keys, but you can acces them with 
// variable name like $first, not with $a[0]
echo $first;

$aa = array_map("addone", $a);
print_r($aa);
?>

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Accepted Solution

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Lukasz Chmielewski earned 2000 total points
ID: 36712542
In most of the cases you would use an array as it is the simplest way of gathering the values.
You would use the list to assign variables to an array elements, and mapping is useful for appying the function to array elements - square function, addition, any defined.
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Author Closing Comment

by:dvcphp
ID: 36712724
Thank you.You explained it so well.Easy to understand.Thanks again.
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LVL 27

Expert Comment

by:Lukasz Chmielewski
ID: 36712749
Thanks. If any further questions, feel free to ask here.
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