Implement Queue using Arrays

queue_implementation.c

// Written by: Md. Maruf Sarker
// Platform: Arch Linux
// Problem: Implement Queue using Arrays
// Language: c
// Date: 2022-11-13

#include <stdio.h>
#include <stdlib.h>

#define size 5
int a[size], i, j, front = -1, rear = -1;

void enqueue(int value){
    if(rear == size - 1) printf( "Queue is full.\n");
    else{
        if (rear + 1 == front) printf( "Queue is full.\n");
        else{
            front = 0;
            rear++;
            a[rear] = value;
            printf("Inserted element: %d\n", a[rear]);
        }
    }
}
void dequeue(){
    if(front == -1) printf("No element to delete.\n");
    else{
        printf("Deleted element: %d\n", a[front]);
        front = front + 1;
        if(front > rear) front = rear = -1;
    }
}
void display(){
    if(rear== -1) printf("Queue is empty!\n");
    else{
        printf("Elements in the queue: ");
        for(int i = front; i <= rear; i++) printf("%d ",a[i]);
    }
}
int main(int argc, char const *argv[]){
    int ch,val;
    do{
        printf("\nMenu");
        printf("\n1. ENQUEUE");
        printf("\n2. DEQUEUE ");
        printf("\n3. DISPLAY QUEUE");
        printf("\n4. Exit");
        printf("\nEnter your choice 1 to 4=");
        scanf("%d",&ch);
        switch (ch){
            case 1:
                printf("Enter the value to be inserted=");
                scanf("%d",&val);
                enqueue(val);
                break;
            case 2:
                dequeue();
                break;
            case 3:
                display();
                break;
            case 4:
                exit(0);
                break;
            default:
                printf("Invalid choice!");
                break;
        }
    }while(ch<=3);
    return 0;
}