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Data Structures
  • Data Structures Manual
  • Arrays
    • Array ADT
    • Linear Search
    • Binary Search
    • Some More Basic Operations
    • Reversing an Array
    • Operations in a Sorted Array
    • Merging Two Arrays
    • Set Operations
    • Finding Missing Elements
    • Duplicates in an Array
    • Getting a Pair whose Sum = K
    • Finding Max & Min in Single Scan
  • Strings
    • Finding the Length of a String
    • Changing Cases in a String
    • Finding Number of Vowels, Consonants & Words
    • Reversing a String
    • Checking for Palindrome
    • Duplicates in a String
    • Checking if Strings are Anagrams
    • Permutations of a String
  • Singly Linked List
    • Displaying the Nodes
    • Counting the Nodes
    • Sum of all Nodes
    • Finding the Maximum Element
    • Searching in a Node
    • Inserting a Node
    • Inserting a Node in Sorted List
    • Deleting a Node
    • Checking if List is Sorted
    • Removing Duplicates from a List
    • Reversing a Linked List
    • Concatenating Two Lists
    • Detecting a Loop in Linked List
    • Merge Two Sorted Lists
    • Finding the Middle Node
  • Cirular Linked List
    • Displaying the Nodes
    • Inserting a Node
    • Deleting a Node
  • Doubly Linked List
    • Inserting a Node
    • Deleting a Node
    • Reversing a Doubly Linked List
    • Circular Doubly Linked List
  • Stack
    • Stack Using Array
    • Stack Using Linked List
    • Balancing Parenthesis
    • Infix to Postfix
    • Evaluation of Postfix Expression
  • Queue
    • Queue using Array
    • Queue using Linked List
    • Double Ended Queue
  • Binary Tree
    • Creating a Binary Tree using Queue
    • Recursive Tree Traversals
    • Iterative Tree Traversals
    • Level Order Traversal
    • Counting Nodes in a Binary Tree
    • Finding the Height of Tree
    • Finding Sum of All Nodes
  • Binary Search Tree
    • Searching in a BST
    • Inserting in a BST
    • Deleting in a BST
  • AVL Tree
    • Inserting in an AVL Tree
    • AVL Tree Rotations
    • Deleting in an AVL Tree
  • Heap
    • Inserting in a Heap
    • Deleting in a Heap
    • Heapify
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  • Queue Structure :
  • Creating a Queue Dynamically :
  • Function to Check if Queue is Empty or Full :
  • En-queue Function :
  • De-queue Function :
  • Display Function :

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  1. Queue

Queue using Array

Implementation of queue using arrays and its functions.

Queue Structure :

struct Queue {
    int size;
    int front;
    int rear;
    int *data;
};

Creating a Queue Dynamically :

struct Queue *createQueue(int size) {

    // Allocating memory for queue
    struct Queue *queue;
    queue = (struct Queue *)malloc(sizeof(struct Queue));
    
    // Set size, front and rear
    queue -> size = size;
    queue -> front = -1;
    queue -> rear = -1;
    
    // Allocating memory for array
    queue -> data = (int *)malloc(size * sizeof(int));
    
    return queue;

}

Function to Check if Queue is Empty or Full :

int isEmpty(struct Queue *queue) {
    return queue -> front == queue -> rear;
}

int isFull(struct Queue *queuevoid display(struct Queue *queue) {
  return queue -> rear == queue -> size - 1;
}

En-queue Function :

void enqueue(struct Queue *queue, int data) {

    if (isFull(queue)) {
        printf("Queue overflow !\n");
        return;
    }
    queue -> rear++;
    queue -> data[queue -> rear] = data;

}

De-queue Function :

int dequeue(struct Queue *queue) {

    if (isEmpty(queue)) {
        printf("Queue underflow !\n");
        return -1;
    }
    queue -> front++;
    int deletedValue = queue -> data[queue -> front];
    return deletedValue;

}

Display Function :

void display(struct Queue *queue) {

    for (int i = queue -> front + 1; i <= queue -> rear; i++) {
        printf("%d\t", queue -> data[i]);
    }
    printf("\n");

}

Contributed by Nitin Ranganath

PreviousEvaluation of Postfix ExpressionNextQueue using Linked List

Last updated 4 years ago

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