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C++ Program to Implement Circular Queue
A queue is an abstract data structure that contains a collection of elements. Queue implements the FIFO mechanism i.e the element that is inserted first is also deleted first.
A circular queue is a type of queue in which the last position is connected to the first position to make a circle.
A program to implement circular queue in C++ is given as follows −
Example
#include <iostream>
using namespace std;
int cqueue[5];
int front = -1, rear = -1, n=5;
void insertCQ(int val) {
if ((front == 0 && rear == n-1) || (front == rear+1)) {
cout<<"Queue Overflow \n";
return;
}
if (front == -1) {
front = 0;
rear = 0;
} else {
if (rear == n - 1)
rear = 0;
else
rear = rear + 1;
}
cqueue[rear] = val ;
}
void deleteCQ() {
if (front == -1) {
cout<<"Queue Underflow\n";
return ;
}
cout<<"Element deleted from queue is : "<<cqueue[front]<<endl;
if (front == rear) {
front = -1;
rear = -1;
} else {
if (front == n - 1)
front = 0;
else
front = front + 1;
}
}
void displayCQ() {
int f = front, r = rear;
if (front == -1) {
cout<<"Queue is empty"<<endl;
return;
}
cout<<"Queue elements are :\n";
if (f <= r) {
while (f <= r){
cout<<cqueue[f]<<" ";
f++;
}
} else {
while (f <= n - 1) {
cout<<cqueue[f]<<" ";
f++;
}
f = 0;
while (f <= r) {
cout<<cqueue[f]<<" ";
f++;
}
}
cout<<endl;
}
int main() {
int ch, val;
cout<<"1)Insert\n";
cout<<"2)Delete\n";
cout<<"3)Display\n";
cout<<"4)Exit\n";
do {
cout<<"Enter choice : "<<endl;
cin>>ch;
switch(ch) {
case 1:
cout<<"Input for insertion: "<<endl;
cin>>val;
insertCQ(val);
break;
case 2:
deleteCQ();
break;
case 3:
displayCQ();
break;
case 4:
cout<<"Exit\n";
break;
default: cout<<"Incorrect!\n";
}
} while(ch != 4);
return 0;
}Output
The output of the above program is as follows −
1)Insert 2)Delete 3)Display 4)Exit Enter choice : 1 Input for insertion: Enter choice : 1 Input for insertion: Enter choice : 1 Input for insertion: Enter choice : 1 Input for insertion: Enter choice : 1 Input for insertion: Enter choice : 2 Element deleted from queue is : 5 Enter choice : 2 Element deleted from queue is : 3 Enter choice : 2 Element deleted from queue is : 2 Enter choice : 1 Input for insertion: 6 Enter choice : 3 Queue elements are : 7 9 6 Enter choice : 4 Exit
Updated on: 25-Jun-2020
22K+ Views
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