Newbie function confusion...

**funkydude9** · 12-14-2002

Basicly, the main purpose of a function is to prevent repeated code, right? So, if you have a set of code that your going to use again and again, you put the code into a function, and then just call the function. My problem is with variables - how do you use a common variable in four different functions? Like if your making an rpg, you would probably need the variable Players_Health. If you have four functions that use this variable, how do you have function1 recogonize the change of the Players_Health in function2 without making a new variable each time in each function?

The only way I know to do this is to initilize and declare the variable in no function (at the very top) which is bad practice.

**abrege** · 12-14-2002

Have you tried declaring parameters?

**Sebastiani** · 12-14-2002

Even worse are functions that reference global variables, though.

Have you used pointers? If not try this:

Code:

void double(int * health){
 *health *= 2;
}
void halve(int * health){
 if(*health)
 *health /= 2;
}

int main(){
int some_health = 12;
cout << "Health: " << some_health << endl;
double(&health);
cout << "Doubled: " <<  some_health << endl;
halve(&health);
cout << "Halved: " << some_health << endl;
cin.get();
return 0;
}

You could use references too which allow you to make permanant changes to the variable but using non-pointer syntax:

Code:

void double(int& health){
 health *= 2;
}
void halve(int& health){
 if(health)
 health /= 2;
}

int main(){
int some_health = 12;
cout << "Health: " << some_health << endl;
double(health);
cout << "Doubled: " <<  some_health << endl;
halve(health);
cout << "Halved: " << some_health << endl;
cin.get();
return 0;
}

Hope that helps...

**funkydude9** · 12-14-2002

Oh yeah...reference parameters! Thx sebastiani

**funkydude9** · 12-14-2002

Wait a sec...

I have a major function, void Start();. I call it many times because it is like the main part of my program. Well, once I'm close to having 50+ variables Start() uses, I don't want each one to be a reference parameter. So how do I make them reference variables inside Start() without initilizing them, so that when i can call it, i can just simply say Start()?

**beege31337** · 12-14-2002

I would group the 50+ variables into a class or classes, and then pass the class by reference.

If you can't figure any way to group the 50+ variables into a class/es, then I guess you could just store them in a array and then pass that to your function.

**funkydude9** · 12-14-2002

No, an array wouldn't really work, and I'm not famililar with classes. Basicly want I want to do something that has the same effect as:

void Start (int &a, int &b, int &c, int &d, int &e....);

without having anything in the parenthesis so that it would look like:

void Start ();

How can I do this?

**Sebastiani** · 12-14-2002

Make them global then. But remember: it is a very bad practice. Have you ever used a struct? A class is the same thing. And, assuming you are using C++, you can add methods to the struct.

Code:

typedef struct Data {
int a;
int b;
int c;
//...etc
void Start(){
a = b;
b = c;
}
};


int main(){
Data data;
data.Start();
return 0;
}

**Imperito** · 12-15-2002

I wouldn't trust Seb...

He is old...

**beege31337** · 12-15-2002

Originally posted by funkydude9

without having anything in the parenthesis so that it would look like:

void Start ();

How can I do this?

If you really don't want to pass any parameters you could do

Code:

#include//whatever

int a;
int b ;
void Start(){
     //you can use a and b in here

}

int main(){

    //you can also use a and b in here

}

but this is bad progamming practice because it can lead to hard to catch side-effects,

you should start to learn how to use classes.

Thread: Newbie function confusion...

Thread Tools

Search Thread

Display

Newbie function confusion...

Similar Threads

Getting an error with OpenGL: collect2: ld returned 1 exit status

Screwy Linker Error - VC2005

How to fix misaligned assignment statements in the source code?

c++ linking problem for x11

I need help with passing pointers in function calls