static private variables not working in c++

Question

I can't understand why static private variable is not working in my code! Here is the code:

#include<iostream>
#include<string>
using namespace std;
class KittyCat{
private:
int a;
string t;
static int count;
public:
KittyCat(){
    a=0;
    t="NULL";
    count++;
}
void set(int i, string m){
    a=i;
    t=m;
}
void show(){
    cout << "A is: "<< a <<" T is: " << t <<"\n\n";
}
void totalCount(){
    cout <<"Total Counts: "<< count <<"\n\n";
}

};
void main(){
KittyCat tech, review, article, photo, video;
tech.set(10, "Technology");
review.set(85, "Reviews");
article.set(54, "Articles");
article.show();
article.totalCount();
}

Any ideas?

Do public static variables work for you when used like this? — juanchopanza, Jun 26 '13 at 05:48
you first need to initialize the static variable. int KittyCat::count=0; — Navin, Jun 26 '13 at 05:49
Instead of (or in addition to) "not working", it's better to say what behavior you expected, and what behavior you observed. — ruakh, Jun 26 '13 at 05:50
You've *declared* `count`, but you've never *defined* it. Add a line like `int KittyCat::count;` after the definition of `KittCat`, but before `main`. — Jerry Coffin, Jun 26 '13 at 05:59
@user1764961 not initialized but define. like Jerry Coffin mentioned — Navin, Jun 26 '13 at 06:01
@Navin, for the second time, the static variable is initialized to 0 by default! — user1764961, Jun 26 '13 at 06:04
@user1764961 thats what i said... the word "initialize" i mentioned is wrong and it should be "define". Like jerry's examples. — Navin, Jun 26 '13 at 06:07
@Navin, no offense, but based on what you wrote, it seems like you still think it's necessary to explicitly assign zero to the 'count'. And that is NOT true. — user1764961, Jun 26 '13 at 06:10
What I meant by my first comment is, if you think `private` has anything to do with it, try `public`. That will help you narrow down your problem. — juanchopanza, Jun 26 '13 at 06:13
@user1764961 yes it's not necessary to initialize it to 0, my mistake. but definitely need to define the static variable. in my first comment i defined and initialized it to 0 because it's a good practice. — Navin, Jun 26 '13 at 06:15

score 0 · Answer 1 · answered Jun 26 '13 at 06:49

0

Even int KittyCat::count; would have also worked. The default value of a static data member is 0. A static data member is declared within the class but defined outside the class definition.

answered Jun 26 '13 at 06:49

Mohammed Farhan Ali

1
2

score -1 · Answer 2 · edited Jun 26 '13 at 06:42

-1

int KittyCat::count = 0;

must be added before main,because all static data member must be initialized before use.

edited Jun 26 '13 at 06:42

Baby Groot

4,637
39
52
71

answered Jun 26 '13 at 06:23

user2522784

1

1

Initializing is a good idea, but given the discussion in the comments to the question, you could have thought about this answer a bit more. – jogojapan Jun 26 '13 at 06:25

score -3 · Answer 3 · answered Jun 26 '13 at 06:07

-3

Got this:

#include<iostream>
#include<string>
using namespace std;
class KittyCat{
private:
int a;
string t;
static int count;
public:
KittyCat(){
    a=0;
    t="NULL";
    count++;
}
void set(int i, string m){
    a=i;
    t=m;
}
void show(){
    cout << "A is: "<< a <<" T is: " << t <<"\n\n";
}
void totalCount(){
    cout <<"Total Counts: "<< count <<"\n\n";
}

};
int KittyCat::count=0;
void main(){
KittyCat tech, review, article, photo, video;
tech.set(10, "Technology");
review.set(85, "Reviews");
article.set(54, "Articles");
article.totalCount();
}

answered Jun 26 '13 at 06:07

Jessica Lingmn

1,162
3
10
15

3

What's this supposed to be? Will you at least explain what the problem was? And could you comment on whether your problem is the same as that described by the possible duplicate question? – jogojapan Jun 26 '13 at 06:08
Program ran and reported `Total Counts: 5`. Looks good to me. What were your expectations? What was "not working" for you? – chux - Reinstate Monica Jun 26 '13 at 06:26
That is not the proper way to answer a question, especially if it's your own. – Ravid Goldenberg Jun 26 '13 at 06:46

static private variables not working in c++

3 Answers3