From:	firewind <firewind AT metroid DOT dyn DOT ml DOT org>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: simple thing
Date:	16 Oct 1997 01:36:07 GMT
Organization:	Netcom
Lines:	44
Message-ID:	<623r27$i73@sjx-ixn3.ix.netcom.com>
References:	<34455CCF DOT 41C6 AT jcu DOT edu DOT au>
NNTP-Posting-Host:	elp-tx1-25.ix.netcom.com
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Oon Lin <Oon DOT Lin AT jcu DOT edu DOT au> wrote:
> Hi !

> I was doing a simple printf but it seems like I don't get the result I
> want...

> The statement was  :

>   printf("Vertical Retrace Time = %f \n", 1/70) ;


> I was careful to use '\n' to force the statement above to be printed out
> but what I got was

>    Vertical Retrace Time = 0.000000


> Wha ??? 


> When I cast the calculation 
>  
>   printf("Vertical Retrace Time = %f \n", (float)(1/70)) ;

> I got the result that I want....

> Is this a bug in GNU ??

No. 1 and 70 are both 'int's. The result of the division of two 'int's is
an 'int', NOT a float. Since the result of 1/70 is a decimal, it is truncated;
in this case to 0. Casting the experssion to a 'float' forced gcc to divide
them as floats. To avoid the cast, you can write:

printf("[...] %f [...]\n", 1.0/70.0);

The decimal places instruct gcc that these numbers are 'float's ('double's 
actually, IIRC) and thus the result of the division is also 'float'.

-- 
[- 				 firewind	                            -]
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[- 	    "You're just jealous because the voices talk to -me-."          -]
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