Hi! i have suse prof 9.3 and i use kdevelope. i have a definition of a class in a .hpp like this:

//prueba.hpp
#include <stdio.h>
#include <iostream>

using namespace std;
class TH_Atender_Cliente //: public Thread
{

public:

static int i;

TH_Atender_Cliente() { i=1;/*pthread_mutex_init(&sem,NULL); */}
~TH_Atender_Cliente() {}
};


and then i have:

//hola.cpp

#include <iostream>
#include "prueba.hpp"
using namespace std;

int main() {

TH_Atender_Cliente unThread;

return 0;
}


Now, the problem is that the kdevelop compile perfecty, even without a single warning... but when i want to compile it with g++, por exsample like this: g++ hola.cpp -o hola
it appear a error like this:

hola.cpp: undefined reference to `TH_Atender_Cliente::i'
collect2: ld returned 1 exit status

In fact, my problem is that i can't use the staticl attribues. For instance, if i have a method than need to use a static attribute, y can't because i have that same error.

Before i did that i had a .cpp where i put the definition of the methods, but thes as i couldn't acces the static attributes, i tried to put all togheter in a .cpp, but the same...

In the example i tried to acces a static attribute in the constructor

please if anyone nows!!!

i think it must be somthing of the g++ because with kdevelope y compile pefectly...

thaks

You need to add the line
after the declaration of the TH_Atender_Cliente class to define "i".

thanks, i did that and it works, but my quistion is: i always have to do that? with all the statics attributes i have? each of them?? i really don't undestood why i have to declear two times the same attribute...why is this??

yes, i know i am a bit newie but i am staring with this lenguaje....

thanks

You declare i here:You define i here:Suppose you didn't create any instances of "TH_Atender_Cliente". The compiler is expecting "i" (one "i") to be defined somewhere. Where, if you don't tell it?

Now suppose you declare a single instance of "TH_Atender_Cliente ". Or better, suppose you declare multiple instances of "TH_Atender_Cliente". Which one defines the "one, true i"? The answer, of course, is none of them.

You always have to define a global variable some one place (and use "extern" to reference it from every other place). The situation is no different for a static class member (like "TH_Atender_Cliente::i).