Question

To save space, we use a circle array to represent a queue. How we decide a queue is empty or full. Set the size of the circle array is N (thr circle array has N positions)

To save space, we use a circle array to represent a queue. How we decide a queue is empty or full. Set the size of the circle way is N (the circle array has N positions) myFront - 0 enqueue 70 enqwewe 80 enqueue 50 myBack - 3 Answer: Full: Empty:

Answer 1

Here is the answer...

Full:

if((myBack==N-1 && myFront==0) || myFront==myBack+1){
       printf("Queue is full\n");
}

Empty:

if(myBack==-1){
       printf("Queue is empty\n");
   }

CODE:

#include <stdio.h>
#define N 5
int que[N],myFront=-1,myBack=-1;
void insert(){
   if((myBack==N-1 && myFront==0)||myFront==myBack+1){
       printf("Queue is full\n");
   }else if(myFront==-1&&myBack==-1){
       printf("Enter Data:");
       scanf("%d",&que[++myBack]);
       myFront++;
   }
   else if(myBack==N-1 && myFront!=0){
       myBack=0;
       printf("Enter data:");
       scanf("%d",&que[myBack]);
   }else{
       printf("Enter data:");
       scanf("%d",&que[++myBack]);
   }
}
void delete(){
   if(myBack==-1){
       printf("Queue is empty\n");
   }else{
       if(myFront==myBack){
           printf("%d is removed\n",que[myBack]);
           myBack=-1;
           myFront=-1;
       }else if(myFront==N-1){
           printf("%d is removed\n",que[myFront]);
           myFront=0;
       }else{
           printf("%d is removed\n",que[myFront++]);
       }
   }
}
void display(){
   int i;
   if(myFront==-1){
       printf("Queue is empty\n");
   }
   else if(myFront<=myBack){
       for(i=myFront;i<=myBack;i++){
           printf("%d\t",que[i]);
       }
       printf("\n");
   }else{
       for(i=myFront;i<=myBack;i++){
           printf("%d\t",que[i]);
       }
       for(i=0;i<=myBack;i++){
           printf("%d\t",que[i]);
       }
       printf("\n");
   }
}
main(){
   int ch;
   do{
       printf("1.Insert\n2.Delete\n3.Display\n4.Exit\n");
       printf("Enter Choice:");
       scanf("%d",&ch);
       switch(ch){
           case 1:
               insert();
               break;
           case 2:
               delete();
               break;
           case 3:
               display();
               break;
           case 4:
               break;
           default:
               printf("You have entered wrong option\n");
               break;
       }
   }while(ch!=4);
}

OUTPUT:

C:\Users\sai\Desktop\circuler_queue.exe 1. Insert 2.Delete 3.Display 4.Exit Enter Choice:1 Enter Data:70 1.Insert 2.Delete 3.Display 4.Exit Enter Choice:1 Enter data:80 1.Insert 2.Delete 3.Display 4.Exit Enter Choice:1 Enter data:50 1.Insert 2.Delete 3.Display 4.Exit Enter Choice:3 70 80 1.Insert 2.Delete 3.Display 4.Exit Enter Choice: 1 Enter data:90 1.Insert 2.Delete 3.Display 4.Exit Enter Choice:3 70 80 90 50 50

50 90 70 80 1.Insert 2.Delete 3.Display 4.Exit Enter Choice:1 Enter data: 100 1.Insert 2.Delete 3.Display 4. Exit Enter Choice:3 70 80 1. Insert 2.Delete 3.Display 4.Exit Enter Choice:1 Queue is full 1.Insert 2.Delete 3.Display 4.Exit Enter Choice: 50 90 100

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