Format quirks
Bart
I am trying to use format to display a set of real numbers in a
particular number of digits. I can control the size of the decimal part
to 2 digits. Is there a way I can specify a maximum length for the
integer part? In my case I would like to limit the length of the result
to 5 characters total. If a number doesn't fit into that length, then
perhaps return "*" instead of the number by going over the length limit.
This is OK:
% format "%5.2f" 12.345
12.35
These are not:
% format "%5.2f" 123.45
123.45
% format "%5.2f" 12345.67
12345.67
suchenwi
> I am trying to use format to display a set of real numbers in a
> particular number of digits. I can control the size of the decimal part
> to 2 digits. Is there a way I can specify a maximum length for the
> integer part? In my case I would like to limit the length of the result
> to 5 characters total. If a number doesn't fit into that length, then
> perhaps return "*" instead of the number by going over the length limit.
Tcl's [format] is very similar to C's sprintf() in that you can
specify a minimum width, but more is taken as needed. You want more
like a FORTRAN model, and in a few lines of code you can have that:
proc strictformat {fmt value} {
set f [format $fmt $value]
regexp {%(\d+)} $fmt -> maxwidth
if {[string length $f]>$maxwidth} {
return [string repeat * $maxwidth]
} else {return $f}
}
% strictformat %5.2f 12.345
12.35
% strictformat %5.2f 123.45
*****
% strictformat %5.2f 1234567
*****
Bart
> Tcl's [format] is very similar to C's sprintf() in that you can
> specify a minimum width, but more is taken as needed. You want more
> like a FORTRAN model, and in a few lines of code you can have that:
>
> proc strictformat {fmt value} {
> set f [format $fmt $value]
> regexp {%(\d+)} $fmt -> maxwidth
> if {[string length $f]>$maxwidth} {
> return [string repeat * $maxwidth]
> } else {return $f}
> }
Thanks for the solution; it will work. However, I was looking for a
solution within the format itself; like a switch that I could use within
regular format strings.
Jonathan Bromley
> However, I was looking for a
>solution within the format itself; like a switch that I could use within
>regular format strings.
But surely that's exactly the point of Tcl... if you don't like what's
there, make your own...
rename format _format
proc format {args} {
if {[string equal [lindex $args 0] -strict]} {
eval strictformat $args
} else {
eval _format $args
}
}
Or if you want to control this strictness item-by-item, you
would need to do a bit more work but it's still possible...
format strings are easy enough to parse.
--
Jonathan Bromley, Consultant
DOULOS - Developing Design Know-how
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The contents of this message may contain personal views which
are not the views of Doulos Ltd., unless specifically stated.
Gerald W. Lester
Ain't none. See the other reply to your post.
Why are you so concerned with only using "solution within the format itself"?
--
+--------------------------------+---------------------------------------+
| Gerald W. Lester |
|"The man who fights for his ideals is the man who is alive." - Cervantes|
+------------------------------------------------------------------------+
Bart
> Ain't none. See the other reply to your post.
>
> Why are you so concerned with only using "solution within the format
> itself"?
>
No reason, really; just laziness. I know it can be done in many ways
(thanks suchenwi and Jonathan) and even on an item by item basis. For
some reason I found it odd that the maximum lengths were not enforced.
Thanks for all replies!
tom.rmadilo
> For
> some reason I found it odd that the maximum lengths were not enforced.
According to the man page, there are no maximum lengths, there are
minimum widths. In %5.2f, the minimum width is 5. This includes the
decimal point. [format %5.2f 1.23] returns ' 1.23', with a space at
the front.