Is `sizeof` in C Evaluated at Compile-Time or Runtime?

Does sizeof in C Depend on Compilation or Runtime?

The sizeof operator in C , as implied by its name, returns the size of a data type or variable. However, a common misconception is whether this size is determined at compilation time or runtime.

Explanation

Contrary to the misconception, sizeof is evaluated at compilation time. This means that it analyzes the source code and determines the size of the data type or variable based on the compiler's settings and the machine it is running on. The result is a constant value that is used throughout the program execution.

For instance, consider the following code snippet:

<code class="c++">sizeof(short int)</code>

This code evaluates to a constant value, regardless of the machine where the program is executed. It does not depend on the size of the underlying data type on the machine running the program.

Conclusion

In summary, sizeof in C is a compile-time operator that calculates the size of a data type or variable based on the compiler's settings at the time of compilation. The result is a fixed value that is used throughout the program's execution, independent of the runtime environment.

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