checking if a var is a number or not

[greenbear]

hi, I want to check if a var. is a number or not. until now i have been using isnum, but it doesnt work with negative numbers.

ie.
.tcl isnum 5 -> Tcl: 1
.tcl isnum -5 -> Tcl: 0

[Petersen]

Didn't I already tell you last nite that isnum isn't a valid tcl command (thus it must be a proc on your bot). For tcl versions 8.1 or higher, [string is double $string] would work. And I still can't be bothered working it out for 8.0.x

[stdragon]

If you only want to tell if it's an integer (positive or negative) you could use this:

Code: Select all

proc is_integer {x} {
  if [catch {incr x}] {return 0}
  return 1
}

For a number with a decimal point, you could do a combination of regexp and expr, i.e. check to see that the string is only "+-.[0-9]", then do, if [catch {expr $x + 1}] to see if it's valid (i.e. doesn't have more than one decimal, etc).

Code: Select all

proc is_real {x} {
  set validchars {^[.+-0123456789].*$}
  if ![regexp $validchars $x] {return 0}
  if [catch {expr $x + 1}] {return 0}
  return 1
}