使用字典中的值检索键

def get_key_by_value(dict_obj, value):
    for key, val in dict_obj.items():
        if val == value:
            return key
    return None  # 如果没有找到匹配的键，则返回None

# 示例字典
my_dict = {'a': 1, 'b': 2, 'c': 3}

# 使用值3检索对应的键
result = get_key_by_value(my_dict, 3)
print(result)  # 输出：c

def get_keys_by_value(dict_obj, value):
    return [key for key, val in dict_obj.items() if val == value]

# 示例字典
my_dict = {'a': 1, 'b': 2, 'c': 3, 'd': 3}

# 使用值3检索对应的键
result = get_keys_by_value(my_dict, 3)
print(result)  # 输出：['c', 'd']