Python中if语句用and做多关键词匹配逻辑异常问题求解

问题根因 #

你编写的if "what"and"about"and"you" in mind判断逻辑不符合Python语法规则，实际执行时会按以下逻辑处理：

• 非空字符串在Python布尔运算中默认判定为True，因此"what"、"about"两个单独的字符串参与运算时，返回值恒为真
• 整个表达式最终等价于仅判断"you" in mind，只要识别结果中存在you关键词，if分支就会触发，完全不会校验另外两个关键词是否存在。如果识别结果误带出you，哪怕语句包含information关键词，也会优先匹配if分支而非后续elif分支。

修复代码 #

将if条件改为分别判断三个关键词是否都存在于mind变量中即可：

greeting()   # greeting mesaage
ear = listen() # listen my voice stored in ear variable
mind = str(recognise(ear)) #recogniser convert it in text by help of google and store in mind variable
        
if "what" in mind and "about" in mind and "you" in mind:
    speak(" i am also fine!")
    speak("what can i do for you?")
elif "information" in mind:
    speak("what you want to know from me, sir!")

拓展写法 #

如果后续需要同时判断的关键词较多，可以使用all()函数简化代码：

check_keys = ["what", "about", "you"]
if all(key in mind for key in check_keys):
    # 对应执行逻辑

内容的提问来源于stack exchange，提问作者Rahul