Why Can\'t I Forward Declare a Typedef in C , and What\'s the Best Alternative?

Forward Declaration of a Typedef in C

The compiler may reject attempts to forward declare a typedef, raising the following question:

Why is forward declaring a typedef not allowed in C ?

Assuming it's indeed impossible, we can explore the best practices for minimizing the size of the inclusion tree.

Answer:

While forward declaring a typedef is generally not allowed in C , there is a solution that involves forward declaring the type being aliased. To define a typedef named B for a type A, follow these steps:

1. Forward declare A:

   class A;

2. Define the typedef:

   typedef A B;

This approach allows you to forward refer to a type that you plan to define later in the codebase, keeping the inclusion tree size manageable.

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