How to use the pushfirst! method of CircularDeque in Julia

Overview

The pushfirst! method is used to add an element at the beginning of the CircularDeque object.

Note: CircularDeque is a double-ended queue implementation using a circular buffer of fixed capacity (while creating the deque, the capacity should be provided). It supports insertion and deletion on both ends.

Syntax

pushfirst!(deque_object, items...) -> collection

Parameter

This method takes an CircularDeque object and the values to be inserted as arguments.

Return value

This method returns the CircularDeque object, which is passed in the arguments.

Example

using DataStructures
#create a new CircularDeque object for 5 elements 
deque = CircularDeque{Int}(5);
push!(deque,2);
push!(deque, 3);
push!(deque, 4);
println("\nDeque ->  $(deque)")
# insert 0 and 1 at the beginning of the deque
pushfirst!(deque, 0, 1);
println("\nDeque ->  $(deque)")

Explanation

  • Line 4: We create a CircularDeque object with the name deque. For this object, we set the capacity as 5, meaning it can hold 5 elements. Also, we set the elements of deque to be an integer datatype.
  • Lines 6–8: We add three integer elements, 2,3, and 4, to deque using the push! method.
  • Line 13: We use the pushfirst! method to add two elements, 0,1, at the beginning of the deque object. After calling this method, the elements of deque will be 0,1,2,3,4 .

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