function DistanceBetween takes unit u, real x, real y returns real
      local real dx = x - GetUnitX(u)
      local real dy = y - GetUnitY(u)
      return SquareRoot(dx * dx + dy * dy)
endfunction

function Distance takes real x, real y, real r returns unit
      local group g = CreateGroup()
      local unit array u
      local real array d
      local integer i = 0
      local integer I = 0
      local unit result
      local real a
      call GroupEnumUnitsInRange(g,x,y,r,null)
      loop
          set u[i] = FirstOfGroup(g)
          exitwhen u[i] == null
          call GroupRemoveUnit(g, u[i])
          set d[i] = DistanceBetween(u[i],x,y)
          set i = i + 1
      endloop
      set a = d[0]
      loop
          set I = I + 1
          exitwhen I == i
          //call BJDebugMsg(I2S(I))
         // call BJDebugMsg(GetUnitName(u[I]))
          //call BJDebugMsg(R2S(d[I]))
          if(a > d[I])then
              set a = d[I]
              set result = u[I]
          endif
          set u[I] = null
      endloop
      call DestroyGroup(g)
      set g = null
      return result
endfunction

//uses: group udg_G, unit udg_U
function GetClosestUnit takes real x, real y, real r, boolexpr b returns unit
     local real d = r * r
     local real dx
     local real dy
     local unit u
     set udg_U = null
     call GroupEnumUnitsInRange(udg_G, x, y, r, b)
     loop
         set u = FirstOfGroup(udg_G)
         exitwhen u == null
         call GroupRemoveUnit(udg_G, u)
         set dx = GetWidgetX(u) - x
         set dy = GetWidgetY(u) - y
         if dx * dx + dy * dy <= d then
             set udg_U = u
             set d = dx * dx + dy * dy
         endif
     endloop
     return udg_U
endfunction