PHP - Ds Deque::allocate() Function

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The PHPDs\Deque::allocate()function allocates enough memory for a required capacity. This function takes the capacity value as input and then allocates the specified memory.

If the specified capacity value is less than or equal to the current capacity, there will be no change, and the old capacity will remain the same. You can check the current capacity using the capacity() function.

Syntax

Following is the syntax of the PHP Ds\Deque::allocate() function −

public Ds\Deque::allocate(int $capacity): void

Parameters

Following is the parameter of this function −

• capacity − It represents the number of values for which the capacity should be allocated.

Return value

This function doesn't return any value.

Example 1

The following is the basic example of the PHP Ds\Deque::allocate() function −

<?php 
   $deque = new \Ds\Deque([1, 2, 3]);
   echo "The deque elements are: \n";
   print_r($deque);
   $capacity = 32;
   echo "The capacity need to be allocated: ".$capacity;
   #using allocate() function
   $deque->allocate($capacity);
?>

Output

The above program produces the following output −

The deque elements are:
Ds\Deque Object
(
    [0] => 1
    [1] => 2
    [2] => 3
)
The capacity need to be allocated: 32

Example 2

Following is another example of the PHP Ds\Deque::allocate() function. We use this function to allocate a new capacity50 tothis deque (["Tutorials", "Point", "India"]) −

<?php 
   $deque = new \Ds\Deque(["Tutorials", "Point", "India"]);
   echo "The deque elements are: \n";
   print_r($deque);
   echo "\nThe capacity before allocated: ";
   print_r($deque->capacity());
   $capacity = 50;
   echo "\nThe capacity need to allocated: ".$capacity;
   #using allocate() function
   $deque->allocate($capacity);
   echo "\nThe capacity after allocated: ";
   print_r($deque->capacity());
?>

Output

After executing the above program, the following output will be displayed −

The deque elements are:
Ds\Deque Object
(
    [0] => Tutorials
    [1] => Point
    [2] => India
)

The capacity before allocated: 8
The capacity need to allocated: 50
The capacity after allocated: 64

Example 3

If the current capacity is greater than the specified capacity, the old capacity will remain the same, and no additional capacity will be allocated −

<?php 
   $deque = new \Ds\Deque(['a', 'b', 'c']);
   echo "The deque elements are: \n";
   print_r($deque);
   echo "\nThe current capacity: ";
   print_r($deque->capacity());
   $capacity = 5;
   echo "\nThe capacity need to allocated: ".$capacity;
   #using allocate() function
   $deque->allocate($capacity);
   echo "\nThe capacity after allocated: ";
   print_r($deque->capacity());
?>

Output

On executing the above program, it displays the following −

The deque elements are:
Ds\Deque Object
(
    [0] => a
    [1] => b
    [2] => c
)

The current capacity: 8
The capacity need to allocated: 5
The capacity after allocated: 8