Re: ceil woes
Re: ceil woes
- Subject: Re: ceil woes
- From: Greg Herlihy <email@hidden>
- Date: Fri, 03 Feb 2006 03:51:18 -0800
- Thread-topic: ceil woes
An "implicit declaration" means that the compiler has not seen any function
declaration to match the function call being made in the source code. For
some reason gcc by default merely warns about this condition when it
sensibly should flag it as an error - nothing good can come from it. (I
recommend adding ?Werror?implicit?function?declaration to XCode's compiler
flags to have gcc report an error when a function declaration appears to be
"missing").
The essential problem here is using floating point routines for what are
essentially integer operations. An in fact the floating point routines are
not really necessary. It's possible to perform the same calculation without
calling any external functions:
mysurvival[i].skillvalue-(int)(calcCircle * 3.5 + 0.5 + 280)*100;
Instead of ceil, add 0.5 to round non-integral results up (since the result
of multiplying an integer by 3.5 will always end in either .0 or .5). The
lround is unnecessary since the value will be truncated. Finally, an "int"
cast should be used to tell the compiler that the float to integer
conversion is intentional.
Greg
On 2/3/06 2:57 AM, "Robert Dell" <email@hidden> wrote:
> ok, i've been TRYING, searching the docs online, searching the /usr/include
> folder, searching for programs that use it for anything that has ceil in it
> but can't find anything to solve my problem.
>
> the bad line is this:
> mysurvival[i].skillreqs =
> mysurvival[i].skillvalue-(lround(ceil((calcCircle*3.5)+280)*100));
>
> mysurvival is defined as:
> struct expskill
> {
> long skillvalue;
> long skillreqs;
> long skillNeeded;
> long skillexclude;
> char skillname[80];
> } myArmor[8], myweapon[25], mymagic[5], mysurvival[15], mylore[13],
> myinstruments[5], swap;
>
> the warnings i'm getting are:
> warning: incompatible implicit declaration of built-in function 'lround'
> warning: incompatible implicit declaration of built-in function 'ceil'
>
> At first, I was just getting the problem with ceil and then noticed it
> returned double. I then decided to convert the double to long and found
> lround which looks to do the trick. All it did was to add yet another
> warning.
>
> any suggestions?
>
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| | >ceil woes (From: Robert Dell <email@hidden>) |