C++ Cheat Sheet

Free C++ cheat sheet: pointers, STL containers, classes, and memory management at a glance.

Basics

Concept	Syntax	Example
Include	`#include <iostream>`	`#include <vector>`
Print	`std::cout << value << std::endl`	`cout << "Hello" << endl;`
Input	`std::cin >> variable`	`cin >> name;`
Namespace	`using namespace std;`	`Avoids writing std:: prefix`

Memory

Concept	Syntax	Example
Pointer	`type* ptr = &var`	`int* p = &x;`
Reference	`type& ref = var`	`int& r = x; // alias for x`
Dynamic alloc	`new / delete`	`int* p = new int(5); delete p;`
Smart pointer	`unique_ptr, shared_ptr`	`auto p = make_unique<int>(42);`

Classes & OOP

Concept	Syntax	Example
Class	`class Name { public: ... };`	`class Dog { public: string name; };`
Constructor	`Name(params) : init { }`	`Dog(string n) : name(n) {}`
Inheritance	`class B : public A { };`	`class Puppy : public Dog {};`
Virtual	`virtual void fn() = 0;`	`Pure virtual = abstract method`

STL Containers

Concept	Syntax	Example
Vector	`vector<T> v`	`vector<int> v = {1, 2, 3};`
Map	`map<K,V> m`	`map<string,int> ages;`
Set	`set<T> s`	`set<int> unique = {1, 2, 3};`
Unordered map	`unordered_map<K,V>`	`unordered_map<string,int> fast;`

Algorithms

Concept	Syntax	Example
Sort	`sort(begin, end)`	`sort(v.begin(), v.end());`
Find	`find(begin, end, val)`	`auto it = find(v.begin(), v.end(), 5);`
Transform	`transform(in, in_end, out, fn)`	`transform(v.begin(), v.end(), v.begin(), [](int x){return x*2;});`
Accumulate	`accumulate(begin, end, init)`	`int sum = accumulate(v.begin(), v.end(), 0);`