C++ Quick Reference

#include <iostream>

int main() {
    std::cout << "Hello\n";
}

int count = 10;

auto price = 9.99;

const int max = 100;

int n;
std::cin >> n;

std::string line;
std::getline(std::cin, line);

#include <format>
std::string s = std::format("{} is {}", name, age);

std::string s = "Ada";

s.size()

s + " Lovelace"

s.substr(0, 3)

s.find("da") != std::string::npos

std::to_string(42)

std::stoi("42")

std::stod("3.5")

a == b

std::vector<int> nums = {3, 1, 2};

nums.push_back(4);

nums[0]

nums.at(0)

nums.size()

for (int n : nums) { }

for (const auto& item : items) { }

std::map<std::string, int> ages;
ages["Ada"] = 36;

std::unordered_map<std::string, int> m;

if (m.contains("Ada")) { }  // C++20

std::set<int> s = {3, 1, 2};

auto p = std::make_pair(1, "a");

auto [x, y] = p;  // structured binding

std::sort(nums.begin(), nums.end());

std::ranges::sort(nums);

std::ranges::sort(users, {}, &User::age);

auto it = std::ranges::find(nums, 3);

std::ranges::count(nums, 3)

std::accumulate(nums.begin(), nums.end(), 0)

auto [lo, hi] = std::ranges::minmax(nums);

std::ranges::reverse(nums);

class Dog {
public:
    explicit Dog(std::string name) : name_(std::move(name)) {}
    std::string bark() const { return "Woof"; }
private:
    std::string name_;
};

class Puppy : public Dog {
    using Dog::Dog;
};

virtual double area() const = 0;

double area() const override { }

auto dog = std::make_unique<Dog>("Rex");

auto cfg = std::make_shared<Config>();

auto add = [](int a, int b) { return a + b; };

[&total](int n) { total += n; }

struct Point { int x = 0; int y = 0; };

try {
    risky();
} catch (const std::exception& e) {
    std::cerr << e.what() << '\n';
}

throw std::runtime_error("something failed");

std::optional<int> find_id(); if (auto id = find_id()) { }

g++ -std=c++20 -Wall main.cpp -o app

clang++ -std=c++20 -O2 main.cpp -o app