Core · Module 7 · Lesson 1 of 11

vector: The Default Container and How It Grows

Store a growing sequence in contiguous memory, understand doubling growth and amortized cost, and never invalidate an iterator by accident again.

ProAbout 10 minutes

By the end you can

Explain why vector storage is contiguous and what that buys
Predict when push_back reallocates and what happens to iterators
Use reserve, size, capacity and shrink_to_fit correctly

Builds on Virtual Functions and Dynamic Dispatch.

01 · A question first

You push a thousand books into a vector and it never asks for a size up front. Some pushes are instant, one mysteriously copies everything. Where does the extra room come from, what does each push really cost, and why do your iterators sometimes die?

Make a guess before you read on.

02 · The idea

Members only

Unlock the full lesson

This lesson is part of the membership. Join to read it in full, along with every other premium deep dive.

What's inside

Start with the problem
How the idea works
Why it is correct
What it costs
Pitfalls and variations
How reserve keeps pointers steady
Original cast examples
Where it is used