• Chris Katko (25/25) Oct 02 2018 - First, I'm confused. The docs say 's' is "whatever it needs to
• Adam D. Ruppe (6/8) Oct 02 2018 That number certainly isn't col.width (unless you have a width of
• Chris Katko (6/14) Oct 02 2018 I'm not sure how I made this mistake. But it seems to only show
• Adam D. Ruppe (8/12) Oct 02 2018 Yeah.

Chris Katko <ckatko gmail.com> writes:

  - First, I'm confused. The docs say 's' is "whatever it needs to 
be". ("he corresponding argument is formatted in a manner 
consistent with its type:") But what if I specifically want a 
STRING. Because I only see floats, ints, etc. No forced string 
types.

  - Second,

This works fine in D:

     printf("%-*s|", col.width-1, col.name.toStringz());

It's a left-aligned, string with a minimum width from the first 
argument, col.width. (-1 because I'm throwing a pipe symbol on 
the end.)

Now with writefln:

     writefln("%-*s|", col.width-1, col.name);

Same format specifier, except I don't need a toStringz which is 
nice. Except it doesn't work and tries to decode col.width-1 into 
a hexadecimal number and only prints that. ("4D6EF6")

I looked through the docs:

https://dlang.org/phobos/std_format.html

  '%' Position Flags Width Separator Precision FormatChar

Width:
     empty
     Integer
     '*'

But there are then zero examples or explanations of how to use 
that option. What's going on here?

Adam D. Ruppe <destructionator gmail.com> writes:

On Wednesday, 3 October 2018 at 00:14:03 UTC, Chris Katko wrote:
 Except it doesn't work and tries to decode col.width-1 into a 
 hexadecimal number and only prints that. ("4D6EF6")

That number certainly isn't col.width (unless you have a width of 
like millions)...

It looks more like a pointer. What is the type of col.name? If it 
is string, this code should work fine.

I'm guessing it is a char*...

Chris Katko <ckatko gmail.com> writes:

On Wednesday, 3 October 2018 at 00:34:33 UTC, Adam D. Ruppe wrote:
 On Wednesday, 3 October 2018 at 00:14:03 UTC, Chris Katko wrote:
 Except it doesn't work and tries to decode col.width-1 into a 
 hexadecimal number and only prints that. ("4D6EF6")

 That number certainly isn't col.width (unless you have a width 
 of like millions)...

 It looks more like a pointer. What is the type of col.name? If 
 it is string, this code should work fine.

 I'm guessing it is a char*...

I'm not sure how I made this mistake. But it seems to only show 
up now if I leave .toStringz() with the writefln.

writefln("%-*s<", col.width-1, col.name.toStringz() /* here */);

So maybe I've been staring at code too long tonight and simply 
missed it?

Adam D. Ruppe <destructionator gmail.com> writes:

On Wednesday, 3 October 2018 at 01:14:24 UTC, Chris Katko wrote:
 I'm not sure how I made this mistake. But it seems to only show 
 up now if I leave .toStringz() with the writefln.

Yeah.

So what's happening here is toStringz returns the C-style char*, 
which printf works well with, but writef doesn't trust it and 
just prints the pointer value instead of trying to traverse it 
looking for a zero terminator (which might not be there).

Just passing a D string will work consistently.

 So maybe I've been staring at code too long tonight and simply 
 missed it?

oh probably, it happens to everyone :)