C++ Cheat Sheet

Learn C++ from the basics →

Basics

std::cout << "Hi" << std::endl;: Console output
std::string name = "Ada";: Standard library string type
auto x = 5;: Type inference
int &ref = x;: Reference — an alias for x, not a pointer

Classes

class Dog { public: void bark(); private: std::string name; };: Class with access specifiers
Dog(std::string n) : name(n) {}: Constructor with a member initializer list
class Dog : public Animal { };: Public inheritance
virtual void speak() = 0;: Pure virtual function (abstract)

STL Containers

std::vector<int> v = {1, 2, 3};: Dynamic array
std::map<std::string, int> m;: Ordered key/value map
std::unordered_map<std::string, int> m;: Hash-based key/value map
std::set<int> s;: Unique, sorted elements

Smart Pointers & RAII

std::unique_ptr<T> p = std::make_unique<T>();: Sole-ownership smart pointer
std::shared_ptr<T> p = std::make_shared<T>();: Reference-counted smart pointer
{ std::lock_guard<std::mutex> lock(m); }: RAII — lock released automatically at scope end

Templates & Lambdas

template<typename T> T max(T a, T b) { return a > b ? a : b; }: Function template
template<typename T> class Box { T value; };: Class template
auto add = [](int a, int b) { return a + b; };: Lambda expression

Exceptions

try { risky(); } catch (const std::exception &e) { }: Catch by const reference
throw std::runtime_error("bad input");: Throw a standard exception type