Queue

/* A program for static ascending priority queue of integers */
#include<stdlib.h>
#include<stdio.h>
#define MAX 5

typedef struct Q
{
int R,F;
int data[MAX];
}Q;

void initialise(Q *P);
int empty(Q *P);
int full(Q *P);
void enqueue(Q *P,int x);
int  dequeue(Q *P);
void print(Q *P);
int main()
{ Q q;
       int op;
       int x;
     initialise(&q);
        do{
printf("\n\n1)Insert\n2)Delete\n3)Print\n4)Quit");
printf("\nEnter Your Choice:");
scanf("%d",&op);
switch(op)
{ case 1: printf("\n Enter a number:");
  scanf("%d",&x);
  if(!full(&q))
enqueue(&q,x);

  else
printf("\nQueue is full !!!!");
  break;
  case 2:if(!empty(&q))
   {
x=dequeue(&q);
printf("\nDeleted Data=%d",x);
   }
  else
printf("\nQueue is empty !!!!");
  break;
  case 3: print(&q);break;
}
      }while(op!=4);
}

void initialise(Q *P)
{
int i;
P->R=-1;
P->F=-1;
}

int empty(Q *P)
{
if(P->R==-1)
return(1);
return(0);
}

int full(Q *P)
{       int places,i;
if(P->R==MAX-1)
 {
places=P->F;
if(places > 0)  //shift the queue
   {
for(i=P->F;i<=P->R;i++)
P->data[i-places]=P->data[i];
P->F=0;
P->R=P->R-places;
for(i=P->R+1;i<MAX;i++)
P->data[i]=NULL;
   }
  }
if(P->R==MAX-1)
return(1);
return(0);
}

void enqueue(Q *P,int x)
{       int i;

if(P->R==-1)
{
P->R=P->F=0;
P->data[P->R]=x;
}
else
{
for(i=P->R;i>=P->F && x<P->data[i];i--)
P->data[i+1]=P->data[i];
P->R=P->R+1;
P->data[i+1]=x;
}
}

int  dequeue(Q *P)
{
int x;
x=P->data[P->F];
if(P->R==P->F)
{
P->R=-1;
P->F=-1;
}
else
P->F=P->F+1;
return(x);
}

void print(Q *P)
{
int i;
if(!empty(P))
{
printf("\n");
for(i=P->F ; i <= P->R ; i=i+1)
printf("%d\t",P->data[i]);
}
}