#include <bits/stdc++.h>
using namespace std;

class Queue
{
    int capacity, size;
    int front, rear;
    int *arr;

public:
    Queue(int capacity)
    {
        this->capacity = capacity;
        front = 0;
        rear = this->capacity - 1;
        arr = new int[capacity];
        size = 0;
    }

    bool isFull()
    {
        return size == capacity;
    }

    bool isEmpty()
    {
        return size == 0;
    }
    
    void display()
    {
        for (int i = 0; i < size; i++)
        {
            // front+i  to prevent changing the position where front is pointing;
            cout << arr[(front + i) % capacity] << ' ';
        }
        cout << endl;
    }

    void enqueue(int data)
    {
        if (isFull())
        {
            return;
        }

        rear = (rear + 1) % capacity;
        arr[rear] = data;
        size++;
        display();
    }

      void dequeue()
    {
        if (isEmpty())
        {
            return;
        }

        front = (front + 1) % capacity;
        size--;
        display();
    }
};

int main()
{
    int capacity;
    cin >> capacity;
    Queue Q(capacity);
    int data;
    for (int i = 0; i < capacity; i++){
      cin >> data;
      Q.enqueue(data);
    }
    
    for (int i = 0; i < capacity; i++){
      Q.dequeue();
    }
    
    return 0;
}
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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}