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The STL from the Inside · 3:34
vector Internals
What the real std::vector looks like inside: three pointers (begin, end, capacity) over a heap block. We watch a full vector double, move its elements across and free the old block, count the work to see why push_back is constant time on average, catch an iterator left pointing at freed memory with AddressSanitizer, and measure what the bounds check in at() really costs on a Mac.
You will learn
- Describe a vector's layout as begin, end and capacity pointers over one heap block
- Explain how push_back grows a full vector and why the average cost stays constant
- Predict when iterators, pointers and references into a vector are invalidated, and use reserve to prevent it
- Choose between operator[] and at() knowing what the bounds check costs