#include <iostream>
#include <string>

class Person {
private:
    std::string name;
    int age;
    static int count;  // Static member

public:
    // Constructor
    Person(const std::string& n, int a) : name(n), age(a) {
        count++;
    }

    // Destructor
    ~Person() {
        count--;
    }

    // Member function
    void introduce() const {
        std::cout << "Hi, I'm " << name << " and I'm " << age << " years old." << std::endl;
    }

    // Static member function
    static int getCount() {
        return count;
    }

    // Getter (const member function)
    std::string getName() const {
        return name;
    }

    // Setter
    void setAge(int a) {
        age = a;
    }

    // Friend function declaration
    friend void displayAge(const Person& p);
};

// Static member initialization
int Person::count = 0;

// Friend function definition
void displayAge(const Person& p) {
    std::cout << p.name << " is " << p.age << " years old." << std::endl;
}

int main() {
    Person alice("Alice", 30);
    Person bob("Bob", 25);

    alice.introduce();
    bob.introduce();

    std::cout << "Total persons: " << Person::getCount() << std::endl;

    displayAge(alice);  // Friend function call

    return 0;
}
by

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

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
}