stringstream fails "streaming" negative values in unsigned types?

Question

I'm having same issue in Ubuntu 10.04 using gcc4.4, the same code works fine on RH 5.5 using gcc4.1

#include <sstream>
#include <iostream>

int main(int argc, char** argv) {

  std::stringstream myStream;
  myStream << "-123";

  unsigned int myUInt;
  myStream >> myUInt;

  if(myStream.fail()) {
    std::cout << "FAILED" << std::endl;
  }
} 

doesn't give FAILED, I have already found this:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39802

where it stated that it was corrected in gcc4.1, not sure the if that miss behave (unless I'm missing something) is related to same problem.

Answer 1

Yes it does.
See here

Answer 2

I'm not sure why you are expecting it to fail. sscanf() also doesn't fail, but reads the the number, and the C++ streams are supposed to work like the scanf functions:

#include <stdio.h>

int main(int argc, char** argv) {
    unsigned int n;
    if ( ! sscanf( "-1", "%ud", & n ) ) {
        printf( "fail\n" );
    }
    else {
        printf( "%ud", n );
    }
} 

prints 4294967295d.

And see also http://stackoverflow.com/questions/786951/stringstream-unsigned-conversion-broken.