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Array Filter array_filter()

Following on from our previous posts showing us lots of lovely PHP Array functions , in this post we are going to delve further into creating our own custom filters for our arrays using array_filter().



The array_filter() function is useful when wanting to use your own function to filter an array based on its values.

The syntax is as follows:

array_filter( array, callbackFunction );

We pass our array in as the first parameter and then the name of our custom function as the second. Below is a basic example of this:

function isNumber( $value )

if( is_numeric( $value ) ) { return( $value ); }


$array    =    array( 

‘value1’ => ‘a’,
‘value2’ => ‘b’,
‘value3’ => 2,
‘value4’ => 3,
‘value5’ => 4            );

print_r( array_filter( $array, ‘isNumber’ ) );

The output of the above would be:

Array ( [value3] => 2 [value4] => 3 [value5] => 4 )

So, what is the above doing? Firstly our array is passed into the array_filter() function, which in turn passes it to our custom callback function isNumber() which we defined above.

All our isNumber() function does is check if each value passed to it is a numeric value or not and if it is it returns it as part of a new array, maintaining its array key value.

In the instance above you can see that the first two values of a and b are not numeric so are ignored, however the values 2, 3 and 4 are numeric and therefore form part of our new array.

The beauty here is that you can make the call back function as simple or as complicated as your heart desires and is a great way to filter out our arrays in a way that other functions might just not accomplish.

Hopefully these functions will help you when filtering your arrays in your PHP Applications. If you would like any help with your PHP development or web projects then why not get in contact with us here at Network Intellect.

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