Solved static variable problem

[Liduen]

Hi guys!

I wanted to test something and wrote this little piece of code:

#include <iostream>
#include <windows.h>
#include <math.h>
#include <string>
using namespace std;

class Player{
public:
	static int nStaticTest;
};


int main(){
	Player::nStaticTest = 1;
	cout << Player::nStaticTest << endl;
	system("Pause");
}

But now i get this error:


Do I really have to "make" an object out of this class first before I can use this static variable?
What am I doing wrong?


Liduen

PS: I already tried this https://guidedhacking.com/showthread.php?3052-Tutorial-Visual-Studio-Linker-Errors&p=11144&viewfull=1#post11144 and it didn't help.

 

[rN']

Create a instanz/object for the Class.

class Player
{
public:
	int	iTest;
};

int main()
{
	// Method 1
	Player*	Test1 = new Player;
	Test1->iTest = 1337;

	//Method 2
	Player	Test2;
	Test2.iTest = 1334;

	printf( "%d\n%d\n", Test1->iTest, Test2.iTest );
	system( "pause" );
	return 0;
}

 

[Liduen]

Do I really have to create an object to use this static variable?

 

[Cyrion]

You can use a function like that but not a variable , because it doesnt exist if you dont create an instance first .

 

[TastyHorror]

Do I really have to create an object to use this static variable?

Taken from wiki...

#include <stdio.h>   

void func() {     
   static int x = 0; // x is initialized only once across three calls of func() and                                  
   // the variable will get incremented three                                   
   //times after these calls. The final value of x will be 3.     
   printf("%d\n", x); // outputs the value of x     
   x = x + 1; 
}   

int main() 
{
   //int argc, char *argv[] inside the main is optional in the particular program     
   func(); // prints 0     
   func(); // prints 1     
   func(); // prints 2     return 0;
 }

So the answer is no.

 

[Liduen]

Okay I tried it like this:

class Player{
public:
	static int nStaticTest;
};

int main(){
	Player Test;
	Test.nStaticTest = 1;
	cout << Test.nStaticTest << endl;
	system("Pause");
	return 0;
}

And I get the same error:

 

[rN']

int nTest

You dont need a static integer

 

[Liduen]

int nTest

You dont need a static integer

Thanks now it works!
- but why not with a static variable?

 

[Syperus]

To use it how you're wanting you need to initialize it

int Player::nStaticTest;

or if you wanted to initialize with a baseline (which is recommended) you could do

int Player::nStaticTest = 1;

So your code will look like

class Player{
public:
    static int nStaticTest;
};
 
int Player::nStaticTest = 1;
 
int main(){
   Player::nStaticTest = 1;
    cout << Player::nStaticTest << endl;
	system("Pause");
}

Whenever using static members within a class you need to declare it globally as if you were prototyping (forward declaration) it. This is because the static variable is a member of the class and not an object of the class so it's treated similarly to a function.