Calling on Functions in Classes

[forceface]

Hello, This part of the code is from something bigger so that is why it is overly complicated. Basically I want to have the numbers 0-9 readout in order with out repeating anything. Here is the code

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <iostream>
#include <math.h>
#include <map>
#include <utility>
#include <vector>
#include <string>

using namespace std;

class CReadout {
    public:
        ~CReadout( );
        CReadout();
        int z;
        void Test();
};


void CReadout::Test(){

cout<<z<<endl;
z++;    
}

CReadout::CReadout( ) {
     Test( );
   
}

CReadout::~CReadout( ) {
	
}

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

What is returned is 0-9 but each digit is repeated 20 times. To test this problem I commented out the whole test function so that it was a void function that did nothing and it still returned 0-9 with each digit is repeated 20 times. I feel like I am missing some fundamental thing. Thanks for any help.

[Athar]

This code will just print a random number (since you forgot to initialize z) and do nothing else.
If you comment out the code in Test(), the program does nothing at all.

When you post a code snippet from a larger program, make sure the problem actually happens with it.

[hanst99]

#include <stdio.h> //should be cstdio
#include <math.h> //should be cmath
#include <time.h> //should be ctime
#include <stdlib.h> //should be cstdlib 

[forceface]

When you say initialize you simply mean int z=0; ( just saying z=0) right?
Well when i do that my compiler gives me the errors:
-forbids initialization of member `z',
-making `z' static ,
-forbids in-class initialization of non-const static member `z'

[zb0S216C]

Class data members cannot be initialized in the same way as ordinary variables. Instead, they must be initialized by the constructors initialization list, like this:

class Class
{
    Class( ) : Z( 0 )
    { }
};

Note the colon after the parameter list of Class's constructor. This is the initialization list of Class::Class( ). However, assigning n to Class::Z is assignment, not initialization. Either way, a variable/data member must be given a value before it's used.

_Wazzak

[forceface]

Can you make data members static variables?

[andywestken]

Do you mean static in the C sense -- as in only visible to the "current compilation unit" (i.e. .cpp file plus all the header it includes) => nope, but you can make an instance of a class static in thise sense.

Or the class sense? => yes. The following declares a static data member for class Class -- which means that all instances of Class see the same value of Z. These cannot be initialized using the constructor's initializer list.

// class.h

class Class
{
public:
    Class ();

    static int Z;
};

// class.cpp

#include <iostream>
// and the other usual suspects
using namespace std;

#include "class.h"

int Class::Z = 0;

int main()
{
    cout << "Z = " << Class::Z << endl;

    return 0;
}

[forceface]

Thank you all sooooo much, this fixed my issues and my understanding of c++ is much better.