function CheckBrackets(string s) as bool
'=======================================
  sys co, le=len s
  byte b at strptr s
  indexbase 0
  for i=0 to <le
    select b(i)
    case "[" : co++
    case "]" : co--
    end select
    if co<0 then return 0
  next
  if co=0 then return 1
end function


'TEST
'====

print CheckBrackets ""    '1
print CheckBrackets "["   '0
print CheckBrackets "]"   '0
print CheckBrackets "[]"  '1
print CheckBrackets "[[]" '0
print CheckBrackets "[]]" '0
print CheckBrackets "[][]"'1
print CheckBrackets "]["  '0