Answer to Question #257238 in C for Jahnvi

Question

Explain queue with the help of an example.

Answer 1

A queue in C is basically a linear data structure to store and manipulate the data elements. t follows the order of First In First Out (FIFO).

In queues, the first element entered into the array is the first element to be removed from the array.

#include <stdio.h>
#define SIZE 100
void enqueue();
void dequeue();
void show();
int inp_arr[SIZE];
int Rear = - 1;
int Front = - 1;
int main() {
    int ch;
    while (1) {
        printf("1.Enqueue Operation\n");
        printf("2.Dequeue Operation\n");
        printf("3.Display the Queue\n");
        printf("4.Exit\n");
        printf("Enter your choice of operations : ");
        scanf("%d", &ch);
        switch (ch) {
          case 1:
            enqueue();
            break;
          case 2:
            dequeue();
            break;
          case 3:
            show();
            break;
          case 4:
            exit(0);
          default:
            printf("Incorrect choice \n");
        } 
    } 
} 
  
void enqueue() {
    int insert_item;
    if (Rear == SIZE - 1) {
       printf("Overflow \n");
    } else {
        if (Front == - 1)
          Front = 0;
        printf("Element to be inserted in the Queue\n : ");
        scanf("%d", &insert_item);
        Rear = Rear + 1;
        inp_arr[Rear] = insert_item;
    }
} 
  
void dequeue() {
    if (Front == - 1 || Front > Rear) {
        printf("Underflow \n");
        return ;
    } else {
        printf("Element deleted from the Queue: %d\n", inp_arr[Front]);
        Front = Front + 1;
    }
} 
  
void show() {
  if (Front == - 1) {
    printf("Empty Queue \n");
  } else {
    printf("Queue: \n");
    for (int i = Front; i <= Rear; i++)
      printf("%d ", inp_arr[i]);
    printf("\n");
  }
}