C++ Basics

Data Types

• Basic Data Types: int, float, double, char, bool, void
• Modifiers: signed, unsigned, short, long
• Derived Types: Arrays (int arr[10];), Pointers (int* ptr;), References (int& ref = var;)
• User-defined Types: struct, enum, class

#include <iostream>
using namespace std;

int main() {
    int a = 10;            // Integer
    float b = 3.14;        // Floating-point
    char c = 'A';          // Character
    bool d = true;         // Boolean
    unsigned int e = 50;   // Unsigned integer

    cout << "Int: " << a << "\nFloat: " << b << "\nChar: " << c
         << "\nBool: " << d << "\nUnsigned Int: " << e << endl;
    return 0;
}

---

Data Structures

Commonly used data structures in C++:

• Arrays: int arr[5] = {1, 2, 3, 4, 5};
• Vectors: Dynamic arrays in the STL (std::vector<int> vec;)
• Linked Lists: Custom implementation or use std::list from the STL.
• Stack and Queue: std::stack and std::queue
• Map and Set: Associative containers like std::map, std::unordered_map, and std::set.

#include <iostream>
#include <vector>
#include <map>
using namespace std;

int main() {
    // Array
    int arr[] = {1, 2, 3, 4, 5};
    cout << "Array: ";
    for (int i : arr) cout << i << " ";
    
    // Vector
    vector<int> vec = {10, 20, 30};
    vec.push_back(40); // Add an element
    cout << "\nVector: ";
    for (int v : vec) cout << v << " ";

    // Map
    map<string, int> age;
    age["Alice"] = 25;
    age["Bob"] = 30;
    cout << "\nMap: ";
    for (auto &pair : age) cout << pair.first << ": " << pair.second << " ";
    
    return 0;
}

Statements

• Control Statements:
  • Conditional: if, else if, else, switch
  • Loops: for, while, do-while
  • Jump: break, continue, return, goto
• Expression Statements: Assignment (=), Arithmetic (+, -, etc.), Logical (&&, ||, !)

#include <iostream>
using namespace std;

int main() {
    int x = 15;

    // If-else statement
    if (x > 10) cout << "x is greater than 10\n";
    else cout << "x is 10 or less\n";

    // Switch statement
    switch (x) {
        case 10: cout << "x is 10\n"; break;
        case 15: cout << "x is 15\n"; break;
        default: cout << "x is unknown\n";
    }

    return 0;
}

Loops

// For Loop
for (int i = 0; i < 10; ++i) {
    std::cout << i << " ";
}

// While Loop
int i = 0;
while (i < 10) {
    std::cout << i++ << " ";
}

// Do-While Loop
int j = 0;
do {
    std::cout << j++ << " ";
} while (j < 10);

Functions

• Function Overloading: Functions with the same name but different parameters.
• Inline Functions: inline int square(int x) { return x * x; }
• Lambda Expressions: auto lambda = [](int x) { return x * x; };

// Declaration and Definition
int add(int a, int b) {
    return a + b;
}

// Function Call
int result = add(5, 3);

Classes

• Concepts:
  • Encapsulation
  • Inheritance
  • Polymorphism
  • Abstraction

class Rectangle {
public:
    int length, width;

    Rectangle(int l, int w) : length(l), width(w) {} // Constructor
    int area() { return length * width; }
};

// Object Instantiation
Rectangle rect(5, 4);
std::cout << "Area: " << rect.area();

Imports

C++ relies on header files for importing functionality:

#include <iostream>  // Input-output operations
#include <vector>    // Dynamic array
#include <map>       // Key-value pairs
#include <string>    // String operations
#include <algorithm> // Standard algorithms (e.g., sort, find)

Common Libraries

• Standard Template Library (STL):
  • Containers: vector, list, map, set, etc.
  • Algorithms: sort, search, transform
  • Iterators: Traverse through containers
• Math Library: <cmath> (e.g., sqrt, pow)
• File I/O: <fstream> for reading and writing files
• Threads: <thread> for multithreading
• Chrono: <chrono> for time-related functions
• Random: <random> for generating random numbers

Example Code

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> nums = {5, 3, 8, 1, 2};
    std::sort(nums.begin(), nums.end()); // Sort the vector

    for (int num : nums) {
        std::cout << num << " ";
    }

    return 0;
}