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From: hjj@athena.mit.edu (Hector Jimenez-Gonzalez)
Newsgroups: comp.sys.amiga.programmer
Subject: SAS/C : -f8 + float + scanf = garbage
Keywords: SAS C scanf
Message-ID: <1991Apr3.220228.24727@athena.mit.edu>
Date: 3 Apr 91 22:02:28 GMT
Sender: news@athena.mit.edu (News system)
Organization: Massachusetts Institute of Technology
Lines: 31


 I have the following problem with SAS/C V5.10: whenever I use the -f8 option 
of "lc" (in order to use the M68881 coprocessor for floating point 
calculations)  and the object used in the "fscanf" or "scanf" is declared as a 
float the value is read in incorrectly. If instead of float I use double 
everything works correctly. As an illustration of this problem look at this 
little program:

#include <stdio.h>
#include <math.h>
#include <m68881.h>

main()
{

      float v;

      while(scanf("%f", &v) == 1)
	    printf("\t%f\n",v);
}

if this is now compiled with lc -f8 -Lm , the printed value does not 
correspond to the input. Changing float to double and %f to %lf in 
"scanf" the problem goes away. 

Has anyone else noticed this problem? If not, could this be harware related?
(I am using an A2500/20).


Hector Jimenez
hjj@athena.mit.edu