Queue operation program .c Programming

 #include <stdio.h>

#include <conio.h>

#define max 3


void main()
{
	int queue[max],data;
	int front,rear,reply,option;

	clrscr();
	//... init queue
	front = rear = 0;
	do
	{
		printf("\n 1. insert queue");
		printf("\n 2. delete queue");
		printf("\n 3. exit");
		printf("\nSelect proper option :");
		scanf("%d",&option);
		switch(option)
		{
			case 1 ://insert
				printf("\nEnter data : ");
				scanf("%d",&data);
				reply = insertq(queue,&front,&rear,&data);
				if ( reply == - 1)
					printf("Que is full");
				else
					printf("Inserted data in queue");
				break;
			case 2 : //dele
				reply = delq(queue,&front,&rear,&data);
				if ( reply == -1 )
					printf("Queue is empty ");
				else
					printf("Deleted data is : %d", data);
				break;
			case 3 : exit(0);
		} //switch
	} while(1);
} // main


int insertq ( int queue[max], int *front, int *rear , int *data)
{
	if (  (*rear + 1 ) % max == *front)
		return(-1);
	else
	{
		*rear = (*rear + 1) % max;
		queue[*rear] = *data;
		return(1);
	} // else
} // insert



int delq( int queue[max], int *front, int *rear , int *data)
{
	if ( *front ==  *rear)
		return(-1);
	else
	{
		*front = (*front + 1 ) % max;
		*data = queue[*front];
		return(1);
	} // else
} // insert