Rear pointer In the Queue

#1

When we don’t have any element then the rear should be -1 then why we are assign the rear pointer to the n-1 index?

#2

hi @Vikaspal

as we are implementing queue using circular array
so we can’t intialize rear with -1
because -1 is not previous to 0
last index is previous to 0 so we point rear to last index

this will be more clear after understanding enqueue operation

bool enqueue(){
		if(!isFull){
			rear=(rear+1)%ms;
			arr[rear]=data;
		}
	}

now for7 size array we point rear to 7-1=6
so before inserting first element
we set rear=(rear+1)%ms
so rear=(6+1)%7=0 hence we are inserting first element at 0th index

but if you set rear=-1 then this will not holds true

i hope this help
if you have more doubts regarding this feel free to ask
if your doubt is resolved mark it as resolved from your doubt section inside your course

#3

@asaurabh_26 got it brother thanks:)