Strange problem with ostringstream 1

xwb · Aug 12, 2009

I'm not sure what is happening with this

Code:

std::ostringstream oss;
oss << "??/??/??";
std::string date = oss.str();
std::cout << date.c_str();

I get \??
If I try

Code:

oss << "??/";

I get a warning about a newline

xwb · Aug 13, 2009

Happens with iostream as well

Code:

#include <iostream>
int main ()
{
   std::cout << "??/??/??" << std::endl;
   return 0;
}

Looks like the / is some sort of regular expression search character. To get the result I want, I have to change it to

Code:

#include <iostream>
int main ()
{
   std::cout << "??\/??\/??" << std::endl;
   return 0;
}

xwb · Aug 13, 2009

Actually that gives warnings, changed to

Code:

#include <iostream>
int main ()
{
   std::cout << "?\?/?\?/??" << std::endl;
   return 0;
}

uolj · Aug 13, 2009

It's a trigraph:

Scroll down to Language Support > C to see why ??/ isn't allowed in C and C++ files.

xwb · Aug 14, 2009

Yet another thing I didn't know about C after using it for 25 years!