Re: C programing problem where <= is interpreted as < when using GCC 11.2.0

[Jonathan Wakely <jwakely.gcc@gmail.com>]

On Thu, 14 Oct 2021 at 16:21, frijolithedog 1 via Gcc-help <
gcc-help@gcc.gnu.org> wrote:

> I am having a C programing problem where <= is interpreted as < when using
> GCC 11.2.0
>
> I was debugging a larger program which I broke down into smaller sections
> of code and I noticed
> the following code was not working correctly:
>
> #include <stdio.h>
> #include <math.h>
> #include <float.h>
>
> int main(void)
>  {
>        float n, step;
>
>        step = 0.1;
>
>            for (n = 2; n <= 10; n = n + step )
>            printf("%3.4f\n", n );                     /*  This stops at
> 9.9000 and not at 10.0000  */
>
>  }
>
> I tried the above code only using the following include statement
> #include <stdio.h>
> but the result was the same.
>


See
https://stackoverflow.com/questions/21895756/why-are-floating-point-numbers-inaccurate
and hundreds of other pages explaining the properties of floating-point
numbers:
https://docs.python.org/3/tutorial/floatingpoint.html
https://en.wikipedia.org/wiki/Floating-point_arithmetic#Representable_numbers,_conversion_and_rounding

For the full story:
https://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html