#include <iostream>
#include <string>

class Base {
protected:
    int value;

public:
    Base(int v) : value(v) {}

    // Using 'this' in operator overloading
    Base& operator+=(int x) {
        this->value += x;
        return *this;
    }

    // Virtual function using 'this'
    virtual void print() const {
        std::cout << "Base: " << this->value << std::endl;
    }

    // Using 'this' to call another member function
    void increment() {
        this->add(1);
    }

private:
    void add(int x) {
        value += x;
    }
};

class Derived : public Base {
private:
    std::string name;

public:
    Derived(int v, const std::string& n) : Base(v), name(n) {}

    // Using 'this' to access both base and derived members
    void print() const override {
        std::cout << "Derived: " << this->name << ", " << this->value << std::endl;
    }

    // Using 'this' to disambiguate between base and derived class methods
    void test() {
        this->Base::print();  // Call base class print
        this->print();        // Call derived class print
    }

    // Using 'this' in a template method
    template<typename T>
    void compareAndPrint(const T& other) const {
        if (this->value > other.value) {
            std::cout << this->name << " is greater" << std::endl;
        } else {
            std::cout << other.name << " is greater or equal" << std::endl;
        }
    }
};

int main() {
    Base b(10);
    b += 5;
    b.print();

    Derived d1(20, "Object1");
    Derived d2(30, "Object2");

    d1.test();

    d1 += 15;
    d1.print();

    d1.compareAndPrint(d2);

    // Using 'this' in polymorphism
    Base* ptr = &d1;
    ptr->print();  // Calls Derived::print()

    return 0;
}
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C++ Online Compiler

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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
}