Are nested functions part of C standard?

Question

Today i came across nested functions which i had never heard of. Is it only part of GNU C?

Here is a wikipedia example of nested function.

float E(fl         


        

Answer 1

No, they are not part of the C or C++ standard. They are a GNU extension in the GCC compiler. See the GCC manual for more information. It is actually possible to take the address of a nested function, which is done using a technique called trampolines, but beware of the caveats listed in the manual.

Answer 2

Nested functions are GCC extension, not a standard C