Path: utzoo!attcan!telly!druid!darcy
From: darcy@druid.uucp (D'Arcy J.M. Cain)
Newsgroups: comp.sys.ibm.pc
Subject: Re: scanf problem in TC v2.01.
Message-ID: <1990Feb19.154506.8830@druid.uucp>
Date: 19 Feb 90 15:45:06 GMT
References: <7192.25d1e107@dit.ie> <25D4D935.3073@maccs.dcss.mcmaster.ca> <25D8649A.24584@maccs.dcss.mcmaster.ca> <204@sdscal.UUCP>
Reply-To: darcy@druid.UUCP (D'Arcy J.M. Cain)
Organization: D'Arcy Cain Consulting, West Hill, Ontario
Lines: 52

In article <204@sdscal.UUCP> keith@sdscal.UUCP (Keith Jones) writes:
>Well, I didn't quite believe it, but I made this test file and sure enough,
>the printf doesn't print out anything that even looks like it approximates
>PI.
>
>----- to cut ----- or not to cut -----
>main()
>{
>    float f;
>    char *string = "3.1415926";
>
>    f = atof( string );
>    printf( "pi = %f\n", f );
>}
>----- be it here ----- or there -----
>
>The output to this program was:
>
>D:\ -> test
>
>-8209.00000
>
>and I compiled it with:
>
>D:\ -> tcc test
>
>I'm not particularly worried about this bug, but I figured I might as well
>post the program.
>
There are a number of things you can do to fix this problem.  The first is
to pull out that reference manual and look up atof's prototype:

double atof(char *str);

Add the above line to your code and it should work.  You may also want to
make f a double and change the printf statement to:

printf( "pi = %lf\n", f );

this will give you a little more precision.

The moral of the story is *ALWAYS* compile with as many warnings turned
on as your compiler will allow and prototype everything.  I do this on
Turbo C, Microsoft C, GNU C and any compiler that allows it and I don't
consider a program correct until it compiles without a whisper.  That
philosophy would have caught the above "bug."

-- 
D'Arcy J.M. Cain (darcy@druid)     |   Thank goodness we don't get all 
D'Arcy Cain Consulting             |   the government we pay for.
West Hill, Ontario, Canada         |
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