static variable problem

[Nasim]

Hi there,

I am little confused with the code below

//afs.cc
#include<fstream>
using std:fstream;

struct A {
static ofstream fout;
};

int main() {
A::fout.open("a.dat");
A::fout.close();
return 0;
}

I think the code is ok. And certainly it compiles (g++ -c afs.cc). But
it fails when I wanted the executable (g++ -o afs afs.cc) and gives the
following error

In function 'main':
: undefined reference to 'Test::fout'
collect2: ld returned 1 exit status

I am really surprised with the happening. Please indicate what I am
missing.

Thank you.

Nasim

 

[Siemel Naran]

//afs.cc
#include<fstream>
using std:fstream;

struct A {
static ofstream fout;
};

Don't forget to define A::fout. What you have above is just a declaration
of fout. Just add the following

ofstream A::fout;