Thread: 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.

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.

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()
}

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