Unions A union is a derived type (similar to a structure) with members that share the same storage space (sometimes the same type of construct needs different types of data).

_Noreturn functions in C C11 added a second function specifier (in addition to `inline') name `_Noreturn', the purpose of this specifier is to inform the user and the compiler that a particular function will not return control to the calling program when it completes execution, informing the user helps to prevent misuse of the function, and informing the compiler may enable it to make some code optimisations.

Inline functions in C Normally, a function call has overhead when being invoked, it takes execution time tp setup the call, pass arguments, jump to the function and return.

Recursion Before we specifically talk about recursion, let's talk about why we might need to use something like recursion.

Variadic Functions in C The word variadic tells us that there is some kind of change, or variation involved, the word variation in a function, means that we are dealing with an unknown number of arguments for a function.

Let’s take a look at some C functions for formatting: