Last updated：2026-10-12
C++ Header-Only vs Implementation Separation¶
I have recently seen some friends ask a few rather interesting questions, so here is a round-up. These are questions that have come up in real interviews — see how many you know and test your fundamentals.
Interview question 1: What style do you usually write code in? Header-only? Or declaration separated from implementation?
Interview question 2: In C++, can every function have its implementation separated from its declaration? Why?
Interview question 3: What methods exist for separating a template's declaration from its implementation? Please illustrate the pros and cons of each with examples, along with their applicable scenarios?
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