OrdinaryQueue.c

//10 a)

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

typedef struct Queue{
    int capacity;
    int*q;
    int front;
    int rear;
}Queue;


void display(Queue*p){
    if(p->front==-1){
        printf("Queue Empty\n");
        return;
    }
    printf("\nQUEUE:\t");
    for(int i=p->front;i<=p->rear;i++){
        printf("%d  ",p->q[i]);
    }
    printf("\n");
}

void enqueue(Queue*p){
    if(p->rear==p->capacity-1){
        printf("Reallocating size...\n");
        int*newarr=(int*)realloc(p->q,p->capacity*2*(sizeof(int)));
        if(newarr==NULL){
            printf("Memory allocation failed...\n");
            return;
        }
        p->q=newarr;
        p->capacity*=2;
    }

    int val;
    printf("Enter the value to enqueue: ");
    scanf("%d",&val);
    if(p->front==-1){
        p->front=0;
    }
    p->q[++p->rear]=val;
}

void dequeue(Queue*p){
    if(p->front==-1){
        printf("Queue Underflow\n");
        return;
    }
    printf("Dequeued value: %d\n",p->q[p->front]);
    for(int i=p->front;i<p->rear;i++){
        p->q[i]=p->q[i+1];
    }
    p->rear--;
    if(p->front>p->rear){
        p->front=p->rear=-1;
    }
}

void peek(Queue*p){
    if(p->front==-1){
        printf("Queue Underflow\n");
        return;
    }
    printf("First Element In Queue-> %d\n",p->q[p->front]);
}

void main(){
    int ch;
    Queue*p=(Queue*)malloc(sizeof(Queue));
    if(p==NULL){
        printf("Memory allocation failed...\n");
        return;
    }

    p->front=p->rear=-1;
    printf("Enter the maximum capacity of the queue: ");
    scanf("%d",&p->capacity);

    p->q=(int*)calloc(p->capacity,sizeof(int));

    for(;;){
        printf("\nENTER:\n1. To enqueue\n2. To display\n3. To dequeue\n4. To peek\n0. To exit\nEnter your choice from above: ");
        scanf("%d",&ch);

        switch(ch){
            case 1:
            enqueue(p);
            break;

            case 2:
            display(p);
            break;

            case 3:
            dequeue(p);
            break;

            case 4:
            peek(p);
            break;

            case 0:
            printf("Exiting...\n");
            exit(0);

            default:
            printf("Invalid Choice! Please Enter Again!\n");
        }
    }
}