Program - Simple Queue

Program -  Simple Queue (Static Queue/ queue implementation using Array)

// Program for Static queue

#include<stdio.h>

#include<conio.h>

#define SIZE 5

int front=-1;

int rear=-1;

int q[SIZE];

void insert();

void del();

void display();

void main()

{

  int choice;

  do

  {

    clrscr();

    printf("\t Menu");

    printf("\n 1. Insert");

    printf("\n 2. Delete");

    printf("\n 3. Display ");

    printf("\n 4. Exit");

    printf("\n Enter Your Choice");

    scanf("%d",&choice);

    switch(choice)

    {

      case 1:

          insert();

          display();

          getch();

          break;

      case 2:

          del();

          display();

          getch();

          break;

      case 3:

          display();

          getch();

          break;

      case 4:

          printf("End of Program");

          getch();

          exit(0);

    }

  }while(choice!=4);

}

void insert()

{

  int no;

  printf("\n Enter No.:");

  scanf("%d",&no);

  if(rear<SIZE-1)

  {

    q[++rear]=no;

    if(front==-1)

      front=0;// front=front+1;

  }

  else

  {

    printf("\n Queue overflow");

  }

}

void del()

{

  if(front==-1)

  {

    printf("\nQueue Underflow");

    return;

  }

  else

  {

    printf("\nElement deleted:-->%d",q[front]);

  }

  if(front==rear)

  {

    front=-1;

    rear=-1;

  }

  else

  {

    front=front+1;

  }

}

void display()

{

  int i;

  if(front==-1)

  {

    printf("\nQueue is empty....");

    return;

  }

  for(i=front;i<=rear;i++)

    printf("\n%d",q[i]);

}