Python函数多条件Or判断逻辑错误：输入Chicago返回Texas

嘿，这是Python新手非常容易踩的逻辑坑！你的条件判断写法有误，导致不管传入什么城市名，第一个if分支都会被触发，所以返回了"Texas"。

错误原因 #

你写的判断条件比如：

if cityName == "dallas" or "austin" or "houston"...

Python会把它解析成：

if (cityName == "dallas") or ("austin") or ("houston")...

而非空字符串在布尔判断中会被视为True，所以只要or后面跟着的是像"austin"这样的非空字符串，这个条件就永远为True——不管cityName是什么，第一个if都会执行，直接返回"Texas"。

两种修正方案 #

方案1：补全每个判断条件

把每个or后面的部分都补全为cityName == "城市名"，确保每个判断都是在比较cityName：

def whatState(cityName):
    if cityName == "dallas" or cityName == "austin" or cityName == "houston" or cityName == "ft worth" or cityName == "el paso":
        stateName = "Texas"
    elif cityName == "sacramento" or cityName == "san francisco" or cityName == "los angeles" or cityName == "san diego":
        stateName = "California"
    elif cityName == "miami" or cityName == "west palm beach" or cityName == "orlando" or cityName == "key west" or cityName == "tallahassee":
        stateName = "Florida"
    elif cityName == "chicago" or cityName == "naperville" or cityName == "peoria" or cityName == "evanston" or cityName == "rockford":
        stateName = "Illinois"
    return stateName

方案2：用in判断（更推荐）

把每个州的城市放到集合里，用cityName in 集合来判断，代码更简洁易读，查找效率也更高：

def whatState(cityName):
    if cityName in {"dallas", "austin", "houston", "ft worth", "el paso"}:
        stateName = "Texas"
    elif cityName in {"sacramento", "san francisco", "los angeles", "san diego"}:
        stateName = "California"
    elif cityName in {"miami", "west palm beach", "orlando", "key west", "tallahassee"}:
        stateName = "Florida"
    elif cityName in {"chicago", "naperville", "peoria", "evanston", "rockford"}:
        stateName = "Illinois"
    # 可选：添加默认分支，避免传入未知城市时报错
    else:
        stateName = "Unknown State"
    return stateName

额外优化建议 #

如果后续要添加更多城市和州，建议用字典来存储映射关系，维护起来更方便：

def whatState(cityName):
    city_to_state = {
        "dallas": "Texas",
        "austin": "Texas",
        "houston": "Texas",
        "ft worth": "Texas",
        "el paso": "Texas",
        "sacramento": "California",
        "san francisco": "California",
        "los angeles": "California",
        "san diego": "California",
        "miami": "Florida",
        "west palm beach": "Florida",
        "orlando": "Florida",
        "key west": "Florida",
        "tallahassee": "Florida",
        "chicago": "Illinois",
        "naperville": "Illinois",
        "peoria": "Illinois",
        "evanston": "Illinois",
        "rockford": "Illinois"
    }
    return city_to_state.get(cityName, "Unknown State")

这样只要维护这个字典就行，不用写一堆if-elif，代码更简洁健壮。

内容的提问来源于stack exchange，提问作者Kristen Norman