working with functions

Hello everyone,

I am working with functions now and tryin to understand them.

I have been practicing different ways for using them.

such as below:

Code:

int greetings();                       // this is a prototype 
 
int age();

int main()
{

	int greetings();                   // this is a function header
	{                                  // start of function body

        char name[20];
		cout << "Please enter your name?  ";
		cin >> name;
		cout << "Hello "<< name <<"\n";

	
	}                                  //end of function body


 cout <<"Enter your age? ";


	    int age();            
		
		{                    
    	int age;

	    cin >> age;
		cout << "You are  " << age << " years old\n\n";

		} 
/* Next I would like to use my greetins function again in        
    my program: */

  int greetings();    // :here                    


	return 0;
}

What I would like to learn next is how to use the same functions over in the program.

I would normally use a loop to repeat this code but I want to know how to reuse the functions in the program.

I've done some rearranging you seem to be used to pascal or something...

Code:

int greetings();                       // this is a prototype 
void age();								//another

int main()
{
	cout <<"Enter your age? ";
	age(); //function call to age (age found outside of main ;) )
	
	/* Next I would like to use my greetins function again in        
		my program: */

	greetings();    // :here                    

	return 0;
}

void age();            
{                    
	int age;

	cin >> age;
	cout << "You are  " << age << " years old\n\n";

} 

int greetings();                   // this is a function header
{                                  // start of function body

    char name[20];
	cout << "Please enter your name?  ";
	cin >> name;
	cout << "Hello "<< name <<"\n";


}         //end of function body

hope that helps

well not pascal but visual c++ 6.0 it came with my book.

I noticed you used void, I forgot about that since age() does not return anything you use void.

I also noticed you added the statement block to the functions after you actually used the

functions. Is that correct?

You define functions in their own block, so you define them outside of the main() function like Boomba did. You can define the functions before or after you used them,
just so long as you have the prototypes before you use them its fine either way.

Code:

void  greetings();                       // change return value to void
void age();

int main()
{
                ...
	return 0;
}

void age();                        // remove the semicolon      
{                    
	...
} 

void greetings();               // remove the semicolon and change return type to void
{                                 
                ...
}

That should do the trick

ok, I believe this is better, not perfect but better. I still need to understand the return and void statement better.

Code:

#include <iostream.h>

int age();
char greetings();

int main()
{
	{
	 greetings();
	}


	{
		age();
	}


   return 0;
}

int age()
{
	int age;
	 cout << "enter your age ";
     cin >> age;
	 cout <<"you are " << age << " years old...\n\n\n";
	return 0;                   
}

char greetings()
{
	char name[20];
     cout << "enter name ";
	 cin >> name;
	 cout << "\nHello " << name << "\n\n";
	return 0;
}

yeah you setup prototypes before and outside of the main function. You can define them after, or you can define them in the prototype like this:

Code:

#include <iostream>

using namespace std;

void age()
{
   ....whatever age does...
};          <---Just remember that ; in the prototype!

int main()
{
    age();
    return 0;
}

or you could do it like this:

Code:

#include <iostream>

using namespace std;

void age();

int main()
{
    age();
    return 0;
}

void age()
{
   ...whatever age does...
}                 <------No semicolon when you define a function after but always put one in the prototype

Good luck!

EDIT: You dont need the

Code:

...
{
         age();
}
...

stuff. Just:

Code:

...
age();
...

will do. And always remember to return a value for main.

Code:

int main()
{
    age();
    greetings();
    return 0;
}

--or you can do--

Code:

int main()
{
     age();
    greetings();
    cin.get()
}

How's this?

Code:

#include <iostream>

using namespace std;

void age();
void greetings();

int main()
{
	
   greetings();
   age();
return 0;
}

void age()              
{
	int age;
	 cout << "enter your age ";
     cin >> age;
	 cout <<"you are " << age << " years old...\n\n\n";
	//return 0;                   
}

void greetings()
{
	char name[20];
     cout << "enter name ";
	 cin >> name;
	 cout << "\nHello " << name << "\n\n";
	                     
}

If you set up your code text editor to only use spaces (not TABS) for indenting code, then everyone else will see the same as you see in your editor, and the same as you see on the forum.
TABS and HTML on forums do not mix.

Originally Posted by robasc

well not pascal but visual c++ 6.0 it came with my book.

I noticed you used void, I forgot about that since age() does not return anything you use void.

I also noticed you added the statement block to the functions after you actually used the

functions. Is that correct?

I had also a visual C++ 6.0 book, it's really anoying what the differents are right now! I had this problem and off course one with the header files and one with the statements with if, else is else... ect!

Here is the format you should use when first learning functions:

Code:

#include <iostream>
#include <string>
using namespace std;

void greeting(string str)
{
    cout<<str<<endl;
}

int main()
{
    greeting("hello");
    greeting("goodbye");
    
    system("PAUSE");
    return 0;
}

I see you used your function header and your prototype together?

could you break your code down and explain what (#include <string>) does?

I haven't seen this one before

I see you used your function header and your prototype together?

You don't need a function prototype if the function is declared before its first use. I like to put them in anyway, though.

The <string> header file was included to use the string class, which is used for the argument of greeting(). A string is sort of like an array of chars, but it resizes itself as required. You don't have buffer overruns with strings.

Code:

char s1[] = "hello ";
strcat(s1, "world!");  // buffer overrun

string s2 = "hello ";
s2 += "world!";  // fine

strings are good for other things too. I'm sure the tutorials have something about them.

Here's the tutorial for strings: http://www.cprogramming.com/tutorial/string.html
And here's the c-string one: http://www.cprogramming.com/tutorial/lesson9.html