BASIC "sgn" function equivalent

Jul 28, 2022

pascal111

Jul 28, 2022

Antonio

Jul 28, 2022

Jul 28, 2022

Jul 28, 2022

Jul 28, 2022

Jul 28, 2022

Jul 28, 2022

Jul 28, 2022

Jul 28, 2022

import std.traits : isFloatingPoint, isIntegral; int sgn(T)(T x) if (isFloatingPoint!T || isIntegral!T) { if(x<0) return -1; else if(x>0) return 1; else return 0; } void main() { import std.stdio; writeln(sgn(-1234)); sgn(-1213.32).writeln; 1234.sgn.writeln; }

On Thursday, 28 July 2022 at 12:02:54 UTC, pascal111 wrote: > I'm making an equivalent of "sgn" function of BASIC language, and I used "(T)" in its definition, but the function can receive wrong data by passing string data to it, how we can solve it? There's no need to do the complication of a template, just do a normal function taking a `double`. You can add overloads if you want like one taking a `long` and/or `int` but those would cover all types that have signs.

On Thu, Jul 28, 2022 at 02:30:38PM +0000, pascal111 via Digitalmars-d-learn wrote: [...] > Of-course D has a built in "sgn" function, but I like to do it with my hands to be sure of code, I'm some doubtful and don't trust alien works. Just use the source, Luke! Phobos is open source for a reason. https://github.com/dlang/phobos/blob/8280b1e7de6cca4dc9a593431591054a5b3aa288/std/math/traits.d#L694 T -- Sometimes the best solution to morale problems is just to fire all of the unhappy people. -- despair.com

On Thursday, 28 July 2022 at 15:03:34 UTC, H. S. Teoh wrote: > On Thu, Jul 28, 2022 at 02:30:38PM +0000, pascal111 via Digitalmars-d-learn wrote: [...] >> Of-course D has a built in "sgn" function, but I like to do it with my hands to be sure of code, I'm some doubtful and don't trust alien works. > > Just use the source, Luke! Phobos is open source for a reason. > > https://github.com/dlang/phobos/blob/8280b1e7de6cca4dc9a593431591054a5b3aa288/std/math/traits.d#L694 > > > T I think Phobos is the big library of D, is it the same one with gdc compiler too? I'm using gdc compiler.

July 28, 2022

Re: BASIC "sgn" function equivalent

Posted by H. S. Teoh
in reply to pascal111

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H. S. Teoh

Posted in reply to pascal111

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On Thu, Jul 28, 2022 at 03:10:19PM +0000, pascal111 via Digitalmars-d-learn wrote:
> On Thursday, 28 July 2022 at 15:03:34 UTC, H. S. Teoh wrote:
> > On Thu, Jul 28, 2022 at 02:30:38PM +0000, pascal111 via Digitalmars-d-learn wrote: [...]
> > > Of-course D has a built in "sgn" function, but I like to do it with my hands to be sure of code, I'm some doubtful and don't trust alien works.
> > 
> > Just use the source, Luke!  Phobos is open source for a reason.
> > 
> > 	https://github.com/dlang/phobos/blob/8280b1e7de6cca4dc9a593431591054a5b3aa288/std/math/traits.d#L694
[...]
> I think Phobos is the big library of D, is it the same one with gdc compiler too? I'm using gdc compiler.

AFAIK, all D compilers ship with full Phobos source code. On my installation, it's in /usr/lib/gcc/x86_64-linux-gnu/11/include/d/*. You can probably find yours in a similar (or the same) location. Under that directory, just look into std/math/*.d for the std.math functions. For example, .sgn is in std/math/traits.d.

In general, all 3 D compilers ship with the same Phobos sources, except perhaps in a few places where some compiler-specific fixes were needed. Generally, though, I think the idea is to merge all such changes upstream under version() blocks so that we can use the same Phobos sources for all compilers.

T

-- 
What's the difference between a 4D tube and an overweight Dutchman?  One is a hollow spherinder, and the other is a spherical Hollander.

On Thursday, 28 July 2022 at 15:38:18 UTC, H. S. Teoh wrote: > On Thu, Jul 28, 2022 at 03:10:19PM +0000, pascal111 via Digitalmars-d-learn wrote: >> > [...] > [...] >> [...] > > AFAIK, all D compilers ship with full Phobos source code. On my installation, it's in /usr/lib/gcc/x86_64-linux-gnu/11/include/d/*. You can probably find yours in a similar (or the same) location. Under that directory, just look into std/math/*.d for the std.math functions. For example, .sgn is in std/math/traits.d. > > In general, all 3 D compilers ship with the same Phobos sources, except perhaps in a few places where some compiler-specific fixes were needed. Generally, though, I think the idea is to merge all such changes upstream under version() blocks so that we can use the same Phobos sources for all compilers. > > > T I checked this path "/usr/lib/gcc/x86_64-linux-gnu/11/include/d/*" yesterday in my Ubuntu. I think you are right. Thanks!

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