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Sort Array Keys

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Scenario - you want to create a list with values from a database. You have a column called names but you only want unique names in the list - no duplicates. Let's take a look at an example array made from a database call.

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$namearray = array("Ana", "Bill", "Claudette", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Grace", "Danny", "Erika", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Grace", "Fabian", "Grace", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Grace")

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As you see we have lots of duplicate names. Luckily PHP has a built in function which removes duplicates from arrays.

array_unique($arraystring); so for our namearray we can do
$namearray = array_unique($namearray); and by using print_r($namearray); we can see what our array now looks like

Array ( [0] => Ana [1] => Bill [2] => Claudette [6] => Danny [7] => Erika [8] => Fabian [9] => Grace )

The problem comes when we try to use a for loop to populate the list. array_unique maintains the original key number (the value between [] ). Ideally we want our array to look like this

Array ( [0] => Ana [1] => Bill [2] => Claudette [3] => Danny [4] => Erika [5] => Fabian [6] => Grace )

if we try our for loop using

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for ($i=0;$i < count($namearray);$i++){
echo $namearray[$i]."<br>";
}

we get : (actual output)

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Ana
Bill
Claudette



Danny

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Erica, Fabian and Grace are missing from the list

What we need to do before executing the for loop is renumber the array keys using :

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$i=0;
foreach ($namearray as $a) {
$mynewarray[$i] = $a;
$i++;
}

foreach only works on arrays and puts each key into the $ after the as - what we do with the key is build a new array. Using print_r($mynewarray); we can see that the keys are now the way we want.

Array ( [0] => Ana [1] => Bill [2] => Claudette [3] => Danny [4] => Erika [5] => Fabian [6] => Grace )

And using the for loop we used before but referencing $mynewarray

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for ($i=0;$i < count($mynewarray);$i++){
echo $mynewarray[$i]."<br>";
}

(actual output)

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Ana
Bill
Claudette
Danny
Erika
Fabian
Grace

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The code

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<? 
//renumbering arrays after array_unique 
//assume this array is built from a database 
$namearray = array("Ana", "Bill", "Claudette", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Grace", "Erika", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Grace", "Fabian", "Grace", "Ana", "Bill", "Claudette", "Danny", "Erika", "Fabian", "Grace"); 
//remove duplicates 
$namearray = array_unique($namearray); 
//build new array with the correct keys 
$i=0; 
foreach ($namearray as $a) { 
$mynewarray[$i] = $a; 
$i++; 
} 
//output the list 
for ($i=0;$i < count($mynewarray);$i++){ 
echo $mynewarray[$i]."<br>"; 
} 
?>

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07 Jan 2004