01 — Modern C++ Mental Model

Core Idea

Modern C++ is not “C with classes.” It is a language for building efficient systems using explicit ownership, deterministic cleanup, value semantics, and zero-cost abstractions.

If you learned C++ around 2008, the biggest shift is this:

Old C++ often taught manual memory management. Modern C++ teaches ownership and RAII.

What Changed Since 2008

C++11 changed the language dramatically. C++14, 17, 20, and 23 continued that direction.

Important modern concepts:

• RAII everywhere.
• Prefer values over raw pointers.
• Prefer standard library types over manual memory.
• Use std::unique_ptr for exclusive ownership.
• Use std::shared_ptr only when ownership is truly shared.
• Understand move semantics.
• Use auto, lambdas, range-for, nullptr, enum class.
• Use CMake, sanitizers, debuggers, and tests.

Modern Style Priorities

Prefer this:

std::vector<std::string> names;

Over this:

char** names;

Prefer this:

auto user = std::make_unique<User>("Ada");

Over this:

User* user = new User("Ada");
delete user;

Prefer this:

for (const auto& item : items) {
    process(item);
}

Over this:

for (int i = 0; i < items.size(); ++i) {
    process(items[i]);
}

What Makes C++ Valuable

C++ is valuable because it exposes reality:

• memory layout,
• object lifetime,
• performance,
• concurrency,
• cache behavior,
• resource ownership,
• undefined behavior,
• hardware and OS boundaries.

This is also why it is hard.

What to Avoid

Avoid writing modern C++ as if it were 1998 C++:

• Avoid owning raw pointers.
• Avoid manual new / delete in normal code.
• Avoid C arrays when std::array or std::vector works.
• Avoid unnecessary inheritance.
• Avoid macros when language features work.
• Avoid clever template code before you understand ordinary code.

Quick Self-Test

You are recovering modern C++ when you can explain:

• Why RAII matters.
• When to use unique_ptr vs shared_ptr.
• What std::move actually does.
• Why std::vector is usually the default container.
• Why undefined behavior is dangerous.
• How to build and debug a small C++ project.