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Structs, Unions & Bitfields

Group related data, overlay the same bytes two ways, and pack flags into bits, plus the padding and alignment rules that decide sizeof and bite packet parsing.

25 min read

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5 interview questions on this topic

Each one opens a full worked answer.

Why is sizeof a struct often larger than the sum of its members?What is a union and when would you use one?What are the portability problems with bitfields?How does a vendor header map a C struct onto hardware registers?What does __attribute__((packed)) do, and what's the cost?

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Structs, Unions & Bitfields | EmbeddedPrep.io