if 0 {[Richard Suchenwirth] 2004-02-11 - Here's a routine for formatting non-negative integers (e.g. file sizes), so that the resulting field width does not exceed 5 characters, of which max. three significant digits, and K(ilo = 1024), M(ega = 1024^2) etc. modifiers are used for scaling. 
This may be useful on small displays.}
----
 proc fixform n {
    if {wide($n) < 1000} {return $n}
    foreach unit {K M G T P E} {
        set n [expr {$n/1024.}]
        if {$n < 1000} {
            set n [string range $n 0 3]
            regexp {(.+)\.$} $n -> n
            return $n$unit
        }
    }
    return Inf ;# :)
 }

if 0 {

[HJG] Test:
}
 proc Demo {n} { puts "$n = [fixform $n]" }

 catch {console show}
 Demo 1
 Demo 20
 Demo 300
 Demo 4000
 Demo 50000
 Demo 600000
 Demo 7000000
 Demo 80000000
 Demo 900000000
 Demo 1000000000
 Demo 11000000000
 Demo 120000000000
 Demo 1300000000000
 Demo 14000000000000
 Demo 150000000000000
 Demo 1600000000000000
 Demo 17000000000000000
 Demo 180000000000000000
 Demo 1900000000000000000

if 0 {

Testing:

 % fixform 1
 1
 % fixform 10
 10
 % fixform 100
 100
 % fixform 1000
 0.97K
 % fixform 10000
 9.76K
 % fixform 100000
 97.6K
 % fixform 1000000
 976K
 % fixform 10000000
 9.53M
 % fixform 100000000
 95.3M
 % fixform 1000000000
 953M
}
----
In the [Tcl chatroom] I was informed that according to http://physics.nist.gov/cuu/Units/binary.html , 
the units based on powers of 2 should be abbreviated 
 Ki Mi Gi Ti Pi Ei
but I haven't seen that used yet... change if you wish.

[DKF]: Some standards are just destined to be ignored...

[slebetman]: The standard is no longer being ignored. New RFC and IEEE documents now use the proper SI form. The documentation for the Linux kernel including comments in the code also use the proper form (kiB = 1024 bytes, kB = 1000 bytes). Still some people insist on ignorance: Americans are still ignoring ''metres'' and ''grams''.

Shouldn't the tests be
  if {wide($n) < 1024} {...
and
  if {$n < 1024} {...
----
[Category String Processing]