Hi guys,

Could anyone tell me what is the effect of the code below, according to the
Standard?

#include <fstream>
#include <ostream>

int main()
{
    std::ofstream os;
    os << "Hello world!" << std::endl;
}

Is this UB? Or should the operator<< fail?

Thanks

---
Gianluca Silvestri

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"Gianluca Silvestri" wrote:

> Could anyone tell me what is the effect of the code below,
> according to the Standard?

> #include <fstream>
> #include <ostream>

> int main()
> {
>     std::ofstream os;
>     os << "Hello world!" << std::endl;
> }

Nothing.  The badbit is set in os, but since you never test it,
that has no effect on anything.

> Is this UB? Or should the operator<< fail?

No undefined behavior.  The operator<< calls sputc on the
filebuf, which (the first time, at least) calls overflow, which
returns EOF is ! is_open().  By convention, any time sputc
returns EOF, an output stream sets badbit.

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