How to concatenate << operator on an instance of MY_object (discards qualifiers error

[tonnot]

I have a class named W_debug. I want to use it at my_oher_class.

I declare it at my_other_class.h

W_debug w_debug;

W_debug w_debug;

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and / or ( To try if it runs...)

W_debug *w_debug

W_debug *w_debug

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;

But the line :

w_debug<<"hello"<<"how areyou";

w_debug<<"hello"<<"how areyou";

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Does not work, compiler gives me the error :

passing 'const W_debug' as 'this' argument of 'W_debug& W_debug:perator<<(const char*)' discards qualifiers

This is my code :
(It works fine if I use it using W_debug()<< , that is to say : without create the instance)

class W_debug
{
public:
    W_debug();
    ~W_debug();
 
  W_debug & operator + (int   data);
  W_debug & operator + (const char data);
  W_debug & operator + (const char * data);
  W_debug & operator + (double data);
.....

class W_debug
{
public:
    W_debug();
    ~W_debug();
   
  W_debug & operator + (int   data);
  W_debug & operator + (const char data);
  W_debug & operator + (const char * data);
  W_debug & operator + (double data);
.....

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And :

W_debug::W_debug() {    }
W_debug::~W_debug(){    }
 
W_debug& W_debug::operator << (const char * data) {    
    os<<data;
    return *this;
......    
 
}

W_debug::W_debug() {    }
W_debug::~W_debug(){    }

W_debug& W_debug::operator << (const char * data) {    
    os<<data;
    return *this;
......    

}

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PS:
I can do something like what I want with 'w_debug' with stringstream :

stringstream os;
os <<data1<<data2;

stringstream os;
os <<data1<<data2;

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I want to do something similar



Any help ? Thanks

[conner686]

Are you storing the w_debug object in another object? If so, it will inherit the const-ness of that object. Somewhere, the object is getting made const, and that's your problem.

Also, I'm guessing you're using Visual C++? W_Debug() << "whatevs" should fail for the same reason, but a MS extention allows such constructs.