/O2 bug?

[Serge Skorokhodov (216716244)]

Hi,

I don't know whether this is a known buf. The following snippet:

== start ==
#include "stdafx.h"
#include <iostream>
#include <tchar.h>

int _tmain(int argc, _TCHAR* argv[])
{
char c[4];
c[0]='a';
c[1]='b';
c[2]='c';
c[3]='d';

std::cout << "before: " << c[0] << c[1] << c[2] << c[3] << " ";

for (int n=2 ; n>0; --n)
{
for (int i=0; i<3; i++)
{
c = c[i+1];
}
c[3] = 'x';
}

std::cout << "after: " << c[0] << c[1] << c[2] << c[3] <<
std::endl;
return 0;
}
== end ==
produces output "before: abcd after: cdxx" without /O2
and "before: abcd: after: cxxx" with /O2

TIA

 

[Carl Daniel [VC++ MVP]]

Hi,

I don't know whether this is a known buf. The following snippet:

Which version are you using?

-cd

 

[Carl Daniel [VC++ MVP]]

== end ==
produces output "before: abcd after: cdxx" without /O2
and "before: abcd: after: cxxx" with /O2

With VC++ 2005 the output is correct with or without /O2.

-cd

 

[Serge Skorokhodov (216716244)]

With VC++ 2005 the output is correct with or without /O2.

-cd

Oh, sorry. I'm using VC++ 2003

 

[Tom Widmer [VC++ MVP]]

Oh, sorry. I'm using VC++ 2003

Confirmed on 2003. The code doesn't look like it has any undefined,
unspecified or implementation defined behaviour.

Tom