Queue Program In C

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We shall see the queue implementation in C programming language here. To learn the theory aspect of queue, click on visit previous page.

Queue Implementation in C

 #include <stdio.h> #include <string.h> #include <stdlib.h> #include <stdbool.h> #define MAX 6 int intArray[MAX]; int front = 0; int rear = -1; int itemCount = 0; int peek() { return intArray[front]; } bool isEmpty() { return itemCount == 0; } bool isFull() { return itemCount == MAX; } int size() { return itemCount; } void insert(int data) { if(!isFull()) { if(rear == MAX-1) { rear = -1; } intArray[&plus;&plus;rear] = data; itemCount&plus;&plus;; } } int removeData() { int data = intArray[front&plus;&plus;]; if(front == MAX) { front = 0; } itemCount--; return data; } int main() { /* insert 5 items */ insert(3); insert(5); insert(9); insert(1); insert(12); // front : 0 // rear : 4 // ------------------ // index : 0 1 2 3 4 // ------------------ // queue : 3 5 9 1 12 insert(15); // front : 0 // rear : 5 // --------------------- // index : 0 1 2 3 4 5 // --------------------- // queue : 3 5 9 1 12 15 if(isFull()) { printf("Queue is full!\n"); } // remove one item int num = removeData(); printf("Element removed: %d\n",num); // front : 1 // rear : 5 // ------------------- // index : 1 2 3 4 5 // ------------------- // queue : 5 9 1 12 15 // insert more items insert(16); // front : 1 // rear : -1 // ---------------------- // index : 0 1 2 3 4 5 // ---------------------- // queue : 16 5 9 1 12 15 // As queue is full, elements will not be inserted. insert(17); insert(18); // ---------------------- // index : 0 1 2 3 4 5 // ---------------------- // queue : 16 5 9 1 12 15 printf("Element at front: %d\n",peek()); printf("----------------------\n"); printf("index : 5 4 3 2 1 0\n"); printf("----------------------\n"); printf("Queue: "); while(!isEmpty()) { int n = removeData(); printf("%d ",n); } } 

Output

If we compile and run the above program, it will produce the following result −

 Queue is full! Element removed: 3 Element at front: 5 ---------------------- index : 5 4 3 2 1 0 ---------------------- Queue: 5 9 1 12 15 16