## digitalmars.D.learn - Complex number syntax

• bearophile (42/42) Nov 11 2007 I don't seem to understand/like D complex number syntax. This little tes...
bearophile <bearophileHUGS lycos.com> writes:
```I don't seem to understand/like D complex number syntax. This little test
program shows complex numbers usage with a struct, and then I have tried to do
the same with the built-in complex reals, and I have failed. Can you help me?
And can the D complex number sintax be made more user-friendly? :-)

The first line also shows yet another problem of writefln, it prints:
2-5i
as
2+-5i

import std.stdio, std.string;

void main() {
writefln("neg im: ", 2-5i);
// Prints: neg im: 2+-5i

struct Complex {
real re, im;
string toString() {
if (im >= 0)
return format(re) ~ '+' ~ format(im) ~ 'i';
else
return format(re) ~ format(im) ~ 'i';
}
}
Complex[8] data1;
foreach(int n, ref d; data1) {
d.re = -n-5;
d.im = n-5;
}
writefln(data1);
// Prints:
// [-5-5i,-6-4i,-7-3i,-8-2i,-9-1i,-10+0i,-11+1i,-12+2i]

cfloat[8] data2;
foreach(int n, ref d; data2) {
// d.re = -n-5; // not possible?
// d.im = n-5; // not possible?
// d = (-n-5, n-5); // not possible
// d = -n-5 + (n-5) i; // not possible
// d = cast(cfloat)(-n-5, n-5); // not possible
d = cast(float)(-n-5) + cast(ifloat)(n-5);
}
writefln(data2);
// Prints:
// [-5+0i,-6+0i,-7+0i,-8+0i,-9+0i,-10+0i,-11+0i,-12+0i]
}

Bye and thank you,
bearophile
```
Nov 11 2007
"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:
```"bearophile" <bearophileHUGS lycos.com> wrote in message
news:fh77bs\$295e\$1 digitalmars.com...

// d = -n-5 + (n-5) i; // not possible

You almost had it there, use

d = (-n - 5) + (n - 5) * 1i;

and it works.
```
Nov 11 2007
"Stewart Gordon" <smjg_1998 yahoo.com> writes:
```"bearophile" <bearophileHUGS lycos.com> wrote in message
news:fh77bs\$295e\$1 digitalmars.com...
<snip>
cfloat[8] data2;
foreach(int n, ref d; data2) {
// d.re = -n-5; // not possible?
// d.im = n-5; // not possible?

These ought to work.

// d = (-n-5, n-5); // not possible

Because (-n-5, n-5) is a comma expression.  It evaluates -n-5, and then
evaulates and returns n-5.

// d = -n-5 + (n-5) i; // not possible

Because i isn't a keyword, it's a literal suffix.

// d = cast(cfloat)(-n-5, n-5); // not possible

<snip>

See above.

Stewart.

--
My e-mail address is valid but not my primary mailbox.  Please keep replies
on the 'group where everybody may benefit.
```
Nov 12 2007