Assertions at Compile Time

In this lesson, we will learn about assertions at compile time in modern C++.

We'll cover the following

static_assert is the tool in modern C++ used to make our code safe.

static_assert

The usage of static_assert is quite easy. static_assert requires an expression and a string. The expression must be predicate that can be evaluated at compile time. Predicate means the expression returns true or false. If the expression evaluates to false, we will get an error message at compile-time with the string as a message. Of course, we get no executable.

There are a few points we must consider.

  • The static_assert expression will be evaluated at compile-time, and we have no runtime overhead.

  • Expressions that can be evaluated at compile time are called constant expressions.

  • We can use static_assert expressions in all parts of our program. Therefore, it is a good idea to put general requirements on our source code in a separate header. As a result, the static_assert expression will be automatically verified at compile time if we include the header. This helps to port our code to a new platform since we can easily check if the new platform supports the type requirements.

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