Copying elements of one queue to another queue : C program

#include <stdio.h>

#define MAX 5

int q1[MAX],q2[MAX],f1=-1,r1=-1,f2=-1,r2=-1;

void enq(int q[],int *f,int *r,int val)

{

                if(*r == MAX-1)

                                printf("queue is full and hence cannot insert");

                else if(*f == -1 && *r == -1)

                                *f=*r=0;

                else

                                *r=*r+1;

                q[*r]=val;

}

void display(int q[],int *f, int *r)

{

                int i;

                if(*f == -1)

                                printf("queue is empty ");

                else

                {

                                for(i=*f;i<=*r;i++)

                                                printf("%d\t",q[i]);

                }             

}

main()

{

                int i,val;

                for(i=0;i<MAX;i++)

                {

                                printf("\nenter a value\n");

                                scanf("%d",&val);

                                enq(q1,&f1,&r1,val);

                }

                printf("\nelements in queue 1 are\n");

                display(q1,&f1,&r1);

               

                for(i=f1;i<=r1;i++)

                                enq(q2,&f2,&r2,q1[i]);

                printf("\nelements in queue 2 are\n");

                display(q2,&f2,&r2);

}

Output: