static_assert

static_assert

Runtime assertions have been a staple of C++ code reliability since the beginning of time. However, there's often been a disagreement over whether or not to leave the assertions in production code, because they inherently slow things down.

The modern answer to this conundrum is the C++ “static_assert” directive. This is like a runtime assertion, but it is fully evaluated at compile-time, so it's super-fast. Failure of the assertion triggers a compile-time error, preventing execution, and the code completely disappears at run-time.

Unfortunately, there really aren't that many things you can assert at compile-time. Most computations are dynamic and stored in variables at runtime. However, the static_assert statement can be useful for things like blocking inappropriate use of template instantiation code, or for portability checking such as:

    static_assert(sizeof(float) == 4, "float is not 32 bits");

This statement is an elegant and language-standardized method to prevent compilation on a platform where a “float” data type is 64-bits, alerting you to a portability problem.

• Next: • Up: Table of Contents • Buy: Generative AI in C++: Coding Transformers and LLMs

The new AI programming book by Aussie AI co-founders: AI coding in C++ Transformer engine speedups LLM models Phone and desktop AI Code examples Research citations Get your copy from Amazon: Generative AI in C++