The Code Gallery

Step 1: If REAR >= SIZE – 1 then
           Write “Queue is Overflow”
Step 2: REAR = REAR + 1
Step 3: QUEUE [REAR] = X
Step 4: If FRONT = -1 then
           FRONT = 0

Step 1: If FRONT = -1 then
           Write “Queue is Underflow”
Step 2: Return QUEUE [FRONT]
Step 3: If FRONT = REAR then
           FRONT = 0
           REAR = 0
           Else
           FRONT = FRONT + 1

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#define SIZE 5
void push(int *QUEUE,int x);
void pop(int *QUEUE);
void display(int *QUEUE);
int FRONT=-1;
int REAR=-1;
int QUEUE[SIZE];
void main()
{
      int x,ch;
      clrscr();
      while(1)
      {
          printf("Select Your Choice:\n");
          printf("(1) PUSH\n");
          printf("(2) POP\n");
          printf("(3) Display\n");
          printf("Enter Your Choice\n");
          scanf("%d",&ch);
          switch(ch)
          {
              case 1:
                   printf("Enter Element:");
                   scanf("%d",&x);
                   push(QUEUE,x);
                   break;
              case 2:
                   pop(QUEUE);
                   break;
              case 3:
                   display(QUEUE);
                   break;
              case 4:
                   exit(0);
          }
}
}
void push(int *QUEUE,int x)
{
      if(REAR>=SIZE-1)
      printf("Queue is Overflow");
      else
      {
          REAR=REAR+1;
          QUEUE[REAR]=x;
          if(FRONT==-1)
          FRONT=0;
      }
}
void pop(int *QUEUE)
{
      if(FRONT==-1)
      printf("Queue is Underflow");
      else
      {
          printf("Deleted Element is %d\n",QUEUE[FRONT]);
          if(FRONT==REAR)
          {
              FRONT=-1;
              REAR=-1;
          }
          else
          {
              FRONT=FRONT+1;
          }
      }
}
void display(int *QUEUE)
{
      int i;
      if(FRONT==-1)
      printf("Queue is Empty\n");
      else
      {
          for(i=FRONT;i<=REAR;i++)
          printf("%d\n",QUEUE[i]);
      }
}