static_assert (compile time assertion)
static_assert is good for testing logic in your code at compilation time.
assert
assert is good for checking a case during run-time that you expect should always have one result, but perhaps could somehow produce an unexpected result under unanticipated circumstances. For example, you should only use assert for determining if a pointer passed into a method is null when it seems like that should never occur. static_assert would not catch that.
Assert compare to if
assert can be used to break program execution, so you could use an if, an appropriate error message, and then halt program execution to get a similar effect, but assert is a bit simpler for that case. static_assert is of course only valid for compilation problem detection while an if must be programmatically valid and can’t evaluate the same expectations at compile-time. (An if can be used to spit out an error message at run-time, however.)
Reference
- https://en.cppreference.com/w/cpp/language/static_assert
- https://stackoverflow.com/questions/18210270/what-is-the-difference-between-assert-and-static-assert