Python遇UnboundLocalError：变量已定义仍提示未绑定的问题求助

错误根源 #

你的get_database函数中，mp004变量仅在for循环内部的if data in i条件成立时才会被赋值。如果输入的data不存在于database的任何元素中，循环结束后mp004从未被初始化，执行return database1[mp004]时就会触发UnboundLocalError。

修复方案 #

推荐直接在找到匹配项时立即返回，避免未初始化变量的问题，同时处理未找到匹配的情况：

def get_database(data,database,database1):
    for c,i in enumerate(database):
        if data in i:
            return database1[c]
    # 处理未找到匹配的场景
    return "未找到对应的回答"

也可以提前初始化变量，再判断是否找到匹配：

def get_database(data,database,database1):
    mp004 = -1  # 提前初始化默认值
    for c,i in enumerate(database):
        if data in i:
            mp004 = c
            break  # 找到后跳出循环，提升效率
    if mp004 == -1:
        return "未找到对应的回答"
    return database1[mp004]

原代码与报错信息 #

原代码：

a = open("dialogs/dialogs.txt").read().splitlines()
def parse(string):
    string = string.lower().split()
    s1 = ""
    for l in string:
        s1+=l[0]
    return s1
def get_database(data,database,database1):
    for c,i in enumerate(database):
        if data in i:
            mp004 = c
    return database1[mp004]

ques = []
anws = []
for c,i in enumerate(a):
    try:
        m = i.split("\t")
        ques.append(parse(m[0]))
        anws.append(m[1])
    except:
        pass
    print(f"Trained {c}/{len(a)-1}            ",end="\r")
    
print()
while True:
    p = input("> ")
    print(get_database(p,ques,anws))

报错信息：

Traceback (most recent call last):
  File "/data/user/0/ru.iiec.pydroid3/files/accomp_files/iiec_run/iiec_run.py", line 31, in <module>
    start(fakepyfile,mainpyfile)
  File "/data/user/0/ru.iiec.pydroid3/files/accomp_files/iiec_run/iiec_run.py", line 30, in start
    exec(open(mainpyfile).read(),  __main__.__dict__)
  File "<string>", line 28, in <module>
  File "<string>", line 12, in get_database
UnboundLocalError: local variable 'mp004' referenced before assignment

内容的提问来源于stack exchange，提问作者user20545517