Basic Pointer Problem

How can we assign a pointer to a function? const char* function_name(), here what exactly does the pointer point to?

Thanks.

In this example, const char * is the type of the return result.

size_t strlen( const char *);
size_t is the return type
const char * is the parameter type.

size_t here is an user-defined return type I believe. How do we implement it? Can you help me with an example? Thanks.

size_t is a type defined by the standard. I think the idea is to solve problems similar to this:

char x[y];

You might think y is an integer. But is it really? What if y is -1? What if y is a number outside the range of valid addressable areas on your computer?

Defining the type as size_t solves these problems because it is guaranteed to work in these situations. But really the bottom line is that if a function returns size_t, then you must either:
a. assign it to a size_t type variable
b. guarantee for yourself that the value returned actually does fit into the variable type you are assigning to

More info:
int - What is size_t in C? - Stack Overflow

Thank YOU. :)