• Egor Starostin (14/14) Dec 26 2006 I have a couple of issues with std.string.format.
• Don Clugston (2/20) Dec 26 2006
• Egor Starostin (3/10) Dec 26 2006 DMD
• Don Clugston (4/15) Jan 03 2007 It uses a different C library (the one which Python was compiled with).
• Frits van Bommel (14/22) Dec 26 2006 Because the format function returns "%1.2f", so writefln expects an
• Egor Starostin (1/6) Dec 26 2006 Indeed! Thank you for an explanation.

Egor Starostin <egorst gmail.com> writes:

I have a couple of issues with std.string.format.

1. why
writefln(format("%%1.%df",2));
produces 'Error: std.format'
but
writefln(format(format("%%1.%df",2),1.0));
works fine?

2. on Windows:
format(format("%%1.%df",4),666666/1000000.0) produces "0.6667"
but
format(format("%%1.%df",4),66666/1000000.0) produces "0.0666"

on Linux second line gives correct answer "0.0667"

What can I do with the second problem? Can anyone suggest a
workaround?

Don Clugston <dac nospam.com.au> writes:

Egor Starostin wrote:
 I have a couple of issues with std.string.format.
 
 1. why
 writefln(format("%%1.%df",2));
 produces 'Error: std.format'
 but
 writefln(format(format("%%1.%df",2),1.0));
 works fine?
 
 2. on Windows:
 format(format("%%1.%df",4),666666/1000000.0) produces "0.6667"
 but
 format(format("%%1.%df",4),66666/1000000.0) produces "0.0666"
 
 on Linux second line gives correct answer "0.0667"

This sounds like a C library issue. Are you using GDC, or DMD ?
 
 What can I do with the second problem? Can anyone suggest a
 workaround?

Egor Starostin <egorst gmail.com> writes:

 2. on Windows:
 format(format("%%1.%df",4),666666/1000000.0) produces "0.6667"
 but
 format(format("%%1.%df",4),66666/1000000.0) produces "0.0666"

 on Linux second line gives correct answer "0.0667"

 This sounds like a C library issue. Are you using GDC, or DMD ?

DMD

In Python for Windows this code works correct. Does this means that Python
doesn't
use C library in such case?

Don Clugston <dac nospam.com.au> writes:

Egor Starostin wrote:
 2. on Windows:
 format(format("%%1.%df",4),666666/1000000.0) produces "0.6667"
 but
 format(format("%%1.%df",4),66666/1000000.0) produces "0.0666"

 on Linux second line gives correct answer "0.0667"

 This sounds like a C library issue. Are you using GDC, or DMD ?

 DMD
 
 In Python for Windows this code works correct. Does this means that Python
doesn't
 use C library in such case?

It uses a different C library (the one which Python was compiled with). 
The one DMD uses was written by Walter, and supports 80-bit floats, for 
example.

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:

Egor Starostin wrote:
 I have a couple of issues with std.string.format.
 
 1. why
 writefln(format("%%1.%df",2));
 produces 'Error: std.format'

Because the format function returns "%1.2f", so writefln expects an 
extra floating-point argument after that string.
What you may be after is
	writefln("%s", format("%%1.%df",2));

 but
 writefln(format(format("%%1.%df",2),1.0));
 works fine?

Here the outer format call returns "1.00" which is a regular string, so 
writefln() doesn't have a problem with it.


If you're passing a string to writefln() that contains % signs you want 
to be sent to the console, either make sure they're properly quoted 
(i.e. %% instead of %) or pass a format string that expects a string 
before it (e.g. "%s").
If you don't want them to be sent to the console but want them to be 
interpreted and substituted, make sure you supply the correct number 
(and type) of arguments...

Egor Starostin <egorst gmail.com> writes:

 1. why
 writefln(format("%%1.%df",2));
 produces 'Error: std.format'

 Because the format function returns "%1.2f", so writefln expects an
 extra floating-point argument after that string.

Indeed! Thank you for an explanation.