php array_push() -> How not to push if the array already contains the value

You check if it's there, using in_array, before pushing.

foreach($something as $value){    if(!in_array($value, $liste, true)){        array_push($liste, $value);    }}

The ,true enables "strict checking". This compares elements using === instead of ==.

php arrays array-push

Two options really.

Option 1: Check for each item and don't push if the item is there. Basically what you're asking for:

foreach($something as $value) {    if( !in_array($value,$liste)) array_push($liste,$value);}

Option 2: Add them anyway and strip duplicates after:

foreach($something as $value) {    array_push($liste,$value);}$liste = array_unique($liste);

By the look of it though, you may just be looking for $liste = array_unique($something);.

php arrays array-push

As this question is using not the best practice code to begin with I find all the answers here to be over-complicated.

Solving code in question:

Basically what is tried to do in question itself is filtering out repetitions. Better approach:

$liste = array_unique($something);

If adding elements to an array that is not empty:

$liste = array_unique(array_merge($liste, $something));

If you are using array_push():

Unless you are actually using return value of array push you should really use:

$liste[] = $value;

for shorter syntax and minor performance increase

CodeHunter