Checking Programming Errors at Compile Time

Assert statements are a simple but very powerful tool for validating invariants and contracts between callers and callees in a codebase. It’s possible to check programming errors while executing the program using assert(). But we should always strive to detect errors as early as possible, and if we have a constant expression, we can catch programming errors when compiling the program using static_assert().

Using assert to trigger errors at runtime

Review the templated version of pow_n(). We want to prevent it from being called with negative exponents (the n value). To prevent this in the runtime version, where n is a regular argument, we can add a runtime assertion: