Overloading <<
Hello,
When writing a class, sometimes I would like to have it output seamlessly to an ostream. For example, say I have a class called Thing.
whereupon it would output something meaningful.
Now suppose I have Thing defined in its own header file, thing.h and implemented in thing.cpp.
Where is the proper place to put the line:
?
My first thought was to include it in thing.h.
Now this works provided I include <iostream> in the header file itself.
But recalling way back (90s) to college when I was taught to use C++, I was told that it is bad form to include a header file in a header file. I should properly include <iostream> in the associated .cpp file and simply have a line like
in the header (I don't remember what this particular technique is called, but it had a name).
When I do this, it won't compile. Can someone tell me the proper way of accomplishing what I intend? Is the only solution to include <iostream> in my thing header file?
BTW the compile error is:
Thanks!
When writing a class, sometimes I would like to have it output seamlessly to an ostream. For example, say I have a class called Thing.
|
|
whereupon it would output something meaningful.
Now suppose I have Thing defined in its own header file, thing.h and implemented in thing.cpp.
Where is the proper place to put the line:
std::ostream& operator<< ( std::ostream& , const Thing& );?
My first thought was to include it in thing.h.
Now this works provided I include <iostream> in the header file itself.
But recalling way back (90s) to college when I was taught to use C++, I was told that it is bad form to include a header file in a header file. I should properly include <iostream> in the associated .cpp file and simply have a line like
class std::ostream;in the header (I don't remember what this particular technique is called, but it had a name).
When I do this, it won't compile. Can someone tell me the proper way of accomplishing what I intend? Is the only solution to include <iostream> in my thing header file?
BTW the compile error is:
bint.h:4:12: error: ‘ostream’ in namespace ‘std’ does not name a type |
Thanks!
| it is bad form to include a header file in a header file |
It's true that under certain conditions and if you're not careful it can greatly increase compile time, but if you have a declaration in a header that needs a declaration that's in another header, there isn't really much you can do, specially with function declarations.
Go ahead and include <iostream>.
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