gcc 4.8.2 runtime library error

gcc 4.8.2 runtime library error

[Arthur Schwarz]

Win 7 64-bit
gcc 4.8.2 (64-bit)

ret: http://stackoverflow.com/questions/23900921/c-scanf-la-returns-0

I don't know whether cygwin or gcc.org maintains the runtime library. If
this is the wrong location I'll redirect this e-mail.

sscanf() doesn't handle "%la" correctly and crashes on "%a". 

Sample code and output:
# include <stdio.h>
# include <ios>
# include <iostream>
# include <iomanip>

#include <cstdlib>

using namespace std;
int main(int argc, char** argv) {
   char buffer[30];
   double x = 5.0;
   sprintf(buffer, "%a", 1.2);
   sscanf(buffer, "%la", &x);
   cout << "    Example 1.2 buffer -> " << buffer << endl;
   cout << "    Example 1.2 scanf <- " << x << endl;

   return 0;
}
output 
 Example 1.2 buffer -> 0x1.3333333333333p+0
 Example 1.2 scanf <- 0



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Re: gcc 4.8.2 runtime library error

[Corinna Vinschen]

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On May 28 08:53, Arthur Schwarz wrote:
> Win 7 64-bit
> gcc 4.8.2 (64-bit)
> 
> ret: http://stackoverflow.com/questions/23900921/c-scanf-la-returns-0
> 
> I don't know whether cygwin or gcc.org maintains the runtime library. If
> this is the wrong location I'll redirect this e-mail.

We're using the stdio functions from the newlib library.

> sscanf() doesn't handle "%la" correctly and crashes on "%a". 

I can't reproduce the crash, but in general, reading hexadecimal
floating point numbers as created by the %a printf format is not
supported in newlib's scanf function family yet.  Nobody provided
a patch for this so far.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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