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* Re: libstdc++/5424: std::ifstream::operator>>(int&) fails with negative hex numbers
@ 2002-01-18 13:51 paolo
0 siblings, 0 replies; 3+ messages in thread
From: paolo @ 2002-01-18 13:51 UTC (permalink / raw)
To: doerntge, gcc-bugs, gcc-prs, nobody
Synopsis: std::ifstream::operator>>(int&) fails with negative hex numbers
State-Changed-From-To: feedback->analyzed
State-Changed-By: paolo
State-Changed-When: Fri Jan 18 13:51:00 2002
State-Changed-Why:
The testcase:
#include <fstream>
#include <iostream>
bool stream_in( void )
{
std::ifstream is( "foo.txt" );
is.setf( std::ios::hex, std::ios::basefield );
int i=0;
if ( !(is.good() && is.is_open()) )
return false;
is >> i;
if ( !is )
return false;
if ( is.peek() == '\n' )
is.ignore();
if ( !is )
return false;
is >> i;
if ( !is )
return false;
if ( is.peek() == '\n' )
is.ignore();
if ( !is )
return false;
return true;
}
bool stream_out( void )
{
std::ofstream os( "foo.txt" );
os.setf( std::ios::hex, std::ios::basefield );
if ( !(os.good() && os.is_open()) )
return false;
os << -42 << '\n' << 42 << '\n';
return true;
}
int main( int argc, char*argv[] )
{
if ( !stream_out() )
std::cerr << "std::ostream failed" << std::endl;
else if ( !stream_in() )
std::cerr << "std::istream failed" << std::endl;
return 0;
}
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5424
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: libstdc++/5424: std::ifstream::operator>>(int&) fails with negative hex numbers
@ 2002-01-19 14:10 paolo
0 siblings, 0 replies; 3+ messages in thread
From: paolo @ 2002-01-19 14:10 UTC (permalink / raw)
To: doerntge, gcc-bugs, gcc-prs, nobody
Synopsis: std::ifstream::operator>>(int&) fails with negative hex numbers
State-Changed-From-To: analyzed->closed
State-Changed-By: paolo
State-Changed-When: Sat Jan 19 14:10:28 2002
State-Changed-Why:
In fact, the behaviour of libstdc++-v3 is strictly standard
conforming. Indeed, according to 22.2.2.2.2, Table 57, the
stdio equivalent of the conversion is %x, thus leading to
ffffffd6 for -42 (i.e., equivalent to printf("%x", -42)).
When the read is attempted it does *not* fit in a signed
int i, and it fails. You can fix your code by using an
unsigned int i.
Cheers,
Paolo.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5424
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: libstdc++/5424: std::ifstream::operator>>(int&) fails with negative hex numbers
@ 2002-01-18 5:04 paolo
0 siblings, 0 replies; 3+ messages in thread
From: paolo @ 2002-01-18 5:04 UTC (permalink / raw)
To: doerntge, gcc-bugs, gcc-prs, nobody
Synopsis: std::ifstream::operator>>(int&) fails with negative hex numbers
State-Changed-From-To: open->feedback
State-Changed-By: paolo
State-Changed-When: Fri Jan 18 05:04:16 2002
State-Changed-Why:
In order to ease the processing of your PR, could you
please provide a self-contained testcase?
Thanks,
Paolo.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5424
^ permalink raw reply [flat|nested] 3+ messages in thread
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2002-01-18 13:51 libstdc++/5424: std::ifstream::operator>>(int&) fails with negative hex numbers paolo
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2002-01-19 14:10 paolo
2002-01-18 5:04 paolo
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