The Ds\Vector::apply() function is an inbuilt function in PHP which is used to update all values in the array by applying the callback function to each value of the vector. After this callback, all the values of the vector will get modified as defined in the callback function.
void public Ds\Vector::apply( $callback )
Parameters: This function accepts a single parameter $callback which is used to update the values in the vector. This callback function should return the value by which vector element is to be replaced.
Return Value: This function does not return any value.
Below programs illustrate the Ds\Vector::apply() function in PHP:
Ds\Vector Object (  => 1  => 2  => 3  => 4  => 5 )
Ds\Vector Object (  => 5  => 10  => 15  => 20  => 25 )