[C++] user defined function w/ returning value

[Chef]

I'm reading this book, Cpp Primer Plus 6th Edition by Stephen Prata. I'm getting into User-defined functions with return values. The code it is using as an example has some parts which I don't quite understand.
I don't understand the function prototype global declaration:
I said "global". Can function prototype's be local? Or are they always global?
int stonetolb(int);
 
The next part I don't understand is at the very end of the code. What is "sts" and when is it supposed to be used?
int stonetolb(int sts) 
{ return 14 * sts;
}

Code: [Select]

#include <iostream>
 
#include <conio.h>
 
int stonetolb(int); // function prototype
 
int main()
   
{
  using namespace std;
 
int stone;
 
cout << "Enter the weight in stone: ";
   
cin >> stone;
  int pounds = stonetolb(stone);
 
cout << stone << " stone = ";
 
cout << pounds << " pounds." << endl;
   
_getch();
  return 0;
   
}
  int stonetolb(int sts)
   
{
  return 14 * sts;
   
}[code] 
 

[flowjob]

Maybe they mean with "global", that the function doesn't belong to a class, so you can call it "global", "foo()" instead of "baz.foo()" (baz is the name of the class) (or however it is done in C++)


"sts" is the name of the variable that is used to temporary store the value that is passed on when calling the function ( stonetolb(stone) ). So "sts" contains the value of "stone" in your example. You then calculate the new weight (14 * sts) and return it...

[Chef]

Maybe they mean with "global", that the function doesn't belong to a class, so you can call it "global", "foo()" instead of "baz.foo()" (baz is the name of the class) (or however it is done in C++)


"sts" is the name of the variable that is used to temporary store the value that is passed on when calling the function ( stonetolb(stone) ). So "sts" contains the value of "stone" in your example. You then calculate the new weight (14 * sts) and return it...

To name the class in C++ "baz" it would be "baz foo()" (No period or parentheses)
What language do you know man? Thanks for answering even though I think you know a language other than C++.

Would you, or anyone reading this, happen to know of a tutorial on function prototypes?
They seem extremely commonplace in C++ so I wanna get a grasp on it.

[flowjob]

What language do you know man? Thanks for answering even though I think you know a language other than C++.

C, Python, Java, PHP

Would you, or anyone reading this, happen to know of a tutorial on function prototypes?
They seem extremely commonplace in C++ so I wanna get a grasp on it.

http://www.cplusplus.com/doc/tutorial/functions2/
seems like a short but good tutorial on functions (and func prototypes)

[dense]

Global means it's accessible everywhere, in every scope.
So locals are the ones you can't access everywhere like functions in a class (the ones that aren't static).

[Chef]

it is, but isn't every function global, if you say it that way?

So I thought, maybe they mean "globally declared", something like declared outside of any class...

That's what I was trying to say/ask. Basically every function prototype that is not in a class is "global" in a sense.
 
 
Okay so I have finally come to the point where I see code and I think of a different way to write it. There is this code in the book that I write in a different way - a way that I am comfortable with.
Let me know the advantages/disadvantages of what I wrote and what is in the book. Personally I like my way a lot more because it's more simple and a lot easier for me to understand.

Code: [Select]

//MY CODE
#include <iostream>
 
#include <conio.h>
 
int random(int);
 
int main(void)
   
{
     int stone;
 
   cout << "Enter the weight in stone: ";
   
   cin >> stone;
     cout << "That weight in stone, in pounds is " << stone*14 << ".\n";
 
   cout << "Thank you and have a nice day.";
   
   _getch();
 
}
 
//THE CODE IN THE BOOK IS BELOW

#include <iostream>
 
int stonetolb(int); // function prototype
 
int main()
 
{
 
using namespace std;
 
int stone;
 
cout << "Enter the weight in stone: ";
 
cin >> stone;
 
int pounds = stonetolb(stone);
 
cout << stone << " stone = ";
 
cout << pounds << " pounds." << endl;
 
return 0;
 
}
 
int stonetolb(int sts)
 
{
 
return 14 * sts;
 
} 
[code] 
 

[flowjob]

Let me know the advantages/disadvantages of what I wrote and what is in the book. Personally I like my way a lot more because it's more simple and a lot easier for me to understand

Your example works aswell, but I guess the books example is about teaching functions, so it wouldn't make any sense doing it without a function. Also, this is just a simplified example. Normally you wouldn't declare a function just for one easy calculation, but when you got several repeating lines of code it would make sense to wrap them in a function instead. Makes troubleshooting a lot easier...

[Chef]

Your example works aswell, but I guess the books example is to teach functions, so it wouldn't make any sense doing it without a function. Also, this is just a simplified example. Normally you wouldn't declare a function just for one easy calculation, but when you got several repeating lines of code it would make sense to wrap them in a function instead. Makes troubleshooting a lot easier...

LOL I just noticed I wrote a function prototype but didn't even use it. I can see how function prototype's will be needed when codes get larger and more complex. Well, I'll get back to the books. I'll get on IRC for sure - in about 2 hours.