python核心編程 第六章練習6-2

6–2. 字串標識符.修改例6-1 的idcheck.py 指令碼,使之可以檢測長度為一的標識符,並且可以識別Python 關鍵字,對後一個要求,你可以使用keyword 模組(特別是keyword.kelist)來幫你.

import stringfrom keyword import iskeywordnums = string.digitscharacters = string.letters + '_'def check(val):length = len(val)if length == 0:print "empty id!"return if val[0] not in characters:print "error! The first character must me '_' or letters "return if iskeyword(value):print "error ! %s is a key word !" % valuereturn others = val[1:]for ch in others:if ch not in (nums+characters):print "error character :%s" % chreturn print 'valid id!'if __name__=="__main__":while True:value = raw_input(">>>\n")value = value.strip()if value == "quit":breakcheck(value)