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Date: Mon, 16 Oct 2006 09:01:11 +1300
From: Danny Smith <dannysmith AT clear DOT net DOT nz>
Subject: Re: Behavior of ifstream::read() in g++
To: Cygwin <cygwin AT cygwin DOT com>
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Alex Vinokur
Sunday, 15 October 2006 5:10 p.m.

> This program has different behavior in
> * g++ 3.4.4 (Cygwin)
> * gpp 4.0.1 *Djgpp)
> * Microsoft C++ 13.00.9466
> 
> ------- foo.cpp ------
> #include <iostream>
> #include <iomanip>
> #include <fstream>
> using namespace std;
> 
> #define BUFFER_SIZE  1500
> #define INPUT_FILE_NAME  "in.txt"
> 
> void foo ()
> {
> char cbuffer[BUFFER_SIZE];
> ifstream fs (INPUT_FILE_NAME);
> 
>   fs.clear();
>   fs.seekg (0, ios::beg);
> 
>   while (!fs.eof())
>   {
>     fs.read (cbuffer, sizeof(cbuffer));
>     cout << "rdstate() = 0x" << hex << fs.rdstate() << dec <<
> "; gcount() = " << fs.gcount() << endl;
>   }
>   cout << "rdstate() = 0x" << hex << fs.rdstate() << dec << endl; }
> 
> int main ()
> {
>   foo ();
>   return 0;
> }
> 
> ----------------------
> 
> 
> Test input file can be seen at
> http://groups.google.com/group/test-av/msg/0c4d3da487594ab7
> 
> 
> Output for g++ (Cygwin)
> --------------------
> rdstate() = 0x6; gcount() = 1499
> rdstate() = 0x6
> -------------------
> It seems that behavior of g++ is wrong here.

This is:
PR libstdc++/20806 & PR libstdc++/21286 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20806

It is fixed in 4.x.

Danny


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