INCLUDE "H6:REALMATH.ACT"
INCLUDE "D2:PRINTF.ACT" ;from the Action! Tool Kit

PROC MiddleThreeDigits(REAL POINTER n CHAR ARRAY res)
  REAL r
  CHAR ARRAY s(15)
  BYTE i

  RealAbs(n,r)
  StrR(r,s)
  i=s(0)
  IF i<3 OR (i&1)=0 THEN
    res(0)=0
  ELSE
    i==RSH 1
    SCopyS(res,s,i,i+2)
  FI
RETURN

PROC Test(CHAR ARRAY s)
  REAL n
  CHAR ARRAY res(4)

  ValR(s,n)
  MiddleThreeDigits(n,res)
  IF res(0) THEN
    PrintF("%9S -> %S%E",s,res)
  ELSE
    PrintF("%9S -> error!%E",s)
  FI
RETURN

PROC Main()
  Put(125) PutE() ;clear the screen

  Test("123")     Test("12345")
  Test("1234567") Test("987654321")
  Test("10001")   Test("-10001")
  Test("-123")    Test("-100")
  Test("100")     Test("-12345")
  Test("1")       Test("2")
  Test("-1")      Test("-10")
  Test("2002")    Test("-2002")
  Test("0")
RETURN