From: dontmailme AT iname DOT com (Steamer)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Library problem?
Date: Sun, 23 Apr 2000 16:14:31 GMT
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To: djgpp AT delorie DOT com
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kalyniuk AT telusplanet DOT net wrote:

>However, the only change I made was to
>change the variable 'bore' from an int to a float. I would have
>thought that the compiler or linker should have thrown up an error or
>warning or something and that my program should have at least shown a
>garbage value (I did use printf to debug) returned from the function
>rather than just ignoring it and leaving it at zero.

If I understand what you did correctly, here's what happened:

Your prototype said that the function expected an int, when in fact
it expected a float.  You passed it a float in the interval (0,1).
Since the compiler thought it was supposed to be an int it converted
it to an int, namely 0 (since it rounds towards 0).  No warning is
given, because float-to-int conversion is entirely normal, specified
by the ANSI standard, etc.  (Note, however, that gcc _will_ warn you
about such implicit conversion if you use the -Wconversion option.)
The function was expecting a float, but a 0 int and a 0 float have
exactly the same representation (four 0 bytes), so it interpreted
the parameter as 0 anyway.

S.