Find the area of a circle using C language

Every program has what is called an "entry point" - a place in the code that the system "knows" will start the application.

It's kind of like a book - when you start reading it, you begin at the first page of text: the introduction or chapter 1, depending.

For a C console app, it's a function called main
So add this below the area function:

int main()
   {
   float r = 0.0f;
   float f = area(f);
   return 0;
   }