Trusted answers to developer questions
Trusted Answers to Developer Questions

Related Tags

php
communitycreator

What is the Ds\Map::allocate() function in PHP?

Khizar Hayat Saani

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

The Map class in PHP is a collection of key-value pairs. The structure of a Map is similar to an array in terms of the sequence (insertion order is preserved), performance, and memory efficiency.

Ds\Map::allocate() is a built-in function in PHP.

The Ds/Map::allocate() function is used to allocate sufficient memory to accommodate the capacity of the Map.

The Ds\Map::allocate() function

Syntax

Below is the function prototype:

void public Ds\Map::allocate($capacity)

Parameters and return value

The Ds\Map::allocate() function takes the following parameter:

  • capacity: An integer value that represents the number of values in Map.

Since the function has a return type of void, nothing is returned.

Note: The capacity will be rounded up to the nearest power of two.

The capacity will remain unchanged if the new capacity is less than or equal to the current capacity of Map.

Code

<?php
// Create a new map 
$map = new \Ds\Map(); 
  
// Use capacity() function to display the default capacity of the map
echo "Default capacity: ";
echo ($map->capacity());
echo "\n";
  
// Allocate new capacity 
$map->allocate(10); 
  
// Display new capacity
echo "New capacity: ";
echo ($map->capacity());
echo "\n";
  
// Allocate capacity again - update
$map->allocate(50); 
  
// Display updated capacity 
echo "Updated capacity: ";
echo ($map->capacity()); 
?>

Output

Default capacity: 8
New capacity: 16
Updated capacity: 64

In the example above, we begin by creating a new map. By default, the capacity of the map is set to 8.

We use the allocate() function to increase the capacity to accommodate 10 values. The map now has a capacity of 16, the next closest power of two.

Then, the map is updated once more using the allocate() function. This time, we pass a capacity of 50 as the input parameter. The capacity of the map is updated to 64, the next closest power of two.

Note: To run this program, you must first install Data Structures for PHP on your local machine.

RELATED TAGS

php
communitycreator

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

Keep Exploring