C++ wrapper iostream input bug

Helmut Jarausch jarausch at igpm.rwth-aachen.de
Mon Mar 22 17:52:18 CET 2010

this is probably a long standing bug since I've encountered it with
several versions of gmp including 5.0.1

The 'operator>>' in the C++ wrapper library fails if the input
is not terminated by white space - see the example.
This doesn't fail for the input operator in general, just for
gmp/gmpxx has been compiled with -O2 on different systems
and different versions of gcc/gmp.
This occurs with g++-4.4.3 but with older versions of g++, as well.

The failing example:

#include <iostream>
#include <sstream>

#include <gmpxx.h>
typedef mpz_class LONG;

int main() {
  std::istringstream  Inp("A9FB57DB"); // works OK if there is a trailing blank
  Inp >> std::hex >> X;
/* terminate called after throwing an instance of 'std::ios_base::failure'
   what():  basic_ios::clear
  std::cout << X << std::endl;


This code should be working just fine.

Helmut Jarausch

Lehrstuhl fuer Numerische Mathematik
RWTH - Aachen University
D 52056 Aachen, Germany

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