Templates & Concepts

What you'll walk away with

Explain the type, lifetime, and runtime behavior of Templates & Concepts
Use warnings and sanitizers to test failure cases
Write modern and safer C++

For Templates & Concepts, reason about container ownership, iterator and range validity, algorithm preconditions, and complexity together. Prefer standard algorithms and ranges over handwritten loops, with explicit mutation and allocation policies.

Build a Complete Mental Model

Apply It in Modern C++

Build an original Templates & Concepts example with `-std=c++23 -Wall -Wextra -Wpedantic` and test empty, boundary, invalid, and failure cases. Run lifetime-sensitive code under AddressSanitizer and UndefinedBehaviorSanitizer.

After This Lesson

Explain the ownership and lifetime contract
Build in C++23 mode with no warnings
Run a boundary or failure test under a sanitizer

cpp

#include <concepts>
#include <iostream>

template <std::integral T>
T twice(T value) { return value * 2; }

int main() { std::cout << twice(21) << '\n'; }

You should see

Try It Yourself

Memory and Safety Warning

Assuming one correct output proves lifetime, bounds, ownership, and undefined behavior are all correct.

The Current ISO C++ Standard (C++23) — Standard C++ Foundation

Easy traps

Assuming one correct output proves lifetime, bounds, ownership, and undefined behavior are all correct.
Assuming a raw pointer or iterator remains valid after its owning container or resource changes.

Hands-on Exercise

You'll know it worked when: 42