Python: KeyError

# 示例1：使用if语句检查键是否存在
my_dict = {'a': 1, 'b': 2, 'c': 3}
if 'd' in my_dict:
    value = my_dict['d']
else:
    value = None

# 示例2：使用try-except语句处理KeyError异常
my_dict = {'a': 1, 'b': 2, 'c': 3}
try:
    value = my_dict['d']
except KeyError:
    value = None

# 示例3：使用字典的get()方法获取键对应的值
my_dict = {'a': 1, 'b': 2, 'c': 3}
value = my_dict.get('d', None)

# 示例4：使用in关键字检查键是否存在
my_dict = {'a': 1, 'b': 2, 'c': 3}
if 'd' in my_dict:
    value = my_dict['d']
else:
    value = None