#1 - Basic Fundamentals - DSA Series With C++ | Akash Vishwakarma

1. Syntax and Control Structures

Basic Syntax

Every C++ program starts with a main function:

int main() {
    // Your code here
    return 0;
}

Variables and Data Types

• Integer types: int, short, long, long long
• Floating-point types: float, double, long double
• Character types: char
• Boolean type: bool
• Void type

Control Structures

If-else Statements

if (condition) {
    // code block
} else if (another_condition) {
    // code block
} else {
    // code block
}

Loops

C++ supports three main types of loops:

// For loop
for (int i = 0; i < n; i++) {
    // code block
}

// While loop
while (condition) {
    // code block
}

// Do-while loop
do {
    // code block
} while (condition);

2. Functions and Recursion

Functions

Functions are blocks of reusable code that perform specific tasks:

return_type function_name(parameters) {
    // function body
    return value;
}

Function Overloading

C++ allows multiple functions with the same name but different parameters:

int add(int a, int b) {
    return a + b;
}

double add(double a, double b) {
    return a + b;
}

Recursion

Recursion is when a function calls itself. Here's a classic example of calculating factorial:

int factorial(int n) {
    if (n <= 1) return 1;
    return n * factorial(n - 1);
}

3. Pointers and Dynamic Memory Allocation

Pointers

Pointers store memory addresses of variables:

int x = 10;
int* ptr = &x;    // & operator gets address of x
cout << *ptr;     // * operator dereferences pointer

Dynamic Memory Allocation

Use new and delete operators for dynamic memory management:

// Single element
int* p = new int;
*p = 10;
delete p;

// Array
int* arr = new int[5];
// use array
delete[] arr;

4. Object-Oriented Programming (OOP)

Classes and Objects

class Person {
private:
    string name;
    int age;
    
public:
    Person(string n, int a) : name(n), age(a) {}
    
    void displayInfo() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

Inheritance

class Student : public Person {
private:
    string studentId;
    
public:
    Student(string n, int a, string id) 
        : Person(n, a), studentId(id) {}
};

Polymorphism

Polymorphism allows objects of different classes to be treated as objects of a common base class:

class Shape {
public:
    virtual double area() = 0;  // Pure virtual function
};

class Circle : public Shape {
private:
    double radius;
public:
    double area() override {
        return 3.14159 * radius * radius;
    }
};

5. Exception Handling and File I/O

Exception Handling

try {
    // code that might throw an exception
    if (someErrorCondition) {
        throw runtime_error("Error message");
    }
} catch (const exception& e) {
    cout << "Error: " << e.what() << endl;
}

File I/O

#include 

// Writing to a file
ofstream outFile("example.txt");
outFile << "Hello, World!" << endl;
outFile.close();

// Reading from a file
ifstream inFile("example.txt");
string line;
while (getline(inFile, line)) {
    cout << line << endl;
}
inFile.close();

Common Interview Questions