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From: ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe)
Newsgroups: comp.lang.c
Subject: Re: i/o of floats
Message-ID: <3598@goanna.cs.rmit.oz.au>
Date: 22 Aug 90 03:20:28 GMT
References: <9232@jpl-devvax.JPL.NASA.GOV>
Organization: Comp Sci, RMIT, Melbourne, Australia
Lines: 24

In article <9232@jpl-devvax.JPL.NASA.GOV>, charest@ai-ganymede.JPL.NASA.GOV (Len Charest) writes:
> I have a large (~40 MB) file of floating point values stored in binary
> [using IEEE-754 single precision (32-bit) format]
> The floats are stored in contiguous "records" of length N, where N is
> determined at *run-time*. This means that I can minimize the number of
> calls to fscanf by reading an entire record of floats from the disk (as
> an array of chars) and then parsing the record in C.

Ick.  You can't use fscanf() with such data *at all*.  fscanf() is for
reading *text*.  To read a record of N bytes as N/4 floats, do

	#define N /*whatever*/
	#define NFLOATS ((N)/sizeof (float))
	float the_record[NFLOATS];
	int floats_read;
	...
	floats_read = fread(the_record, sizeof (float), NFLOATS, the_stream);

Now you have 32-bit floats in memory and can do
	printf("%g", the_record[floats_read-1])
or whatever takes your fancy.

-- 
The taxonomy of Pleistocene equids is in a state of confusion.