Python3 exceptionprocessingtutorial

try:
    # 可能会引发exception code
    pass
except [ExceptionType [as e]]:
    # processingexception code
    pass

# basic exceptionprocessing
try:
    num = int(input("请输入一个number: "))
    result = 10 / num
    print(f"结果 is : {result}")
except:
    print("发生了error！")

# 捕获specificexception
try:
    num = int(input("请输入一个number: "))
    result = 10 / num
    print(f"结果 is : {result}")
except ValueError:
    print("输入error, 请输入一个 has 效 number！")
except ZeroDivisionError:
    print("error: 除数不能 for 零！")
except Exception as e:
    print(f"发生了othererror: {e}")

# 捕获 many 个exception
try:
    num = int(input("请输入一个number: "))
    result = 10 / num
    print(f"结果 is : {result}")
except (ValueError, ZeroDivisionError) as e:
    print(f"发生了error: {e}")

# usingelse子句
try:
    num = int(input("请输入一个number: "))
    result = 10 / num
except ValueError:
    print("输入error, 请输入一个 has 效 number！")
except ZeroDivisionError:
    print("error: 除数不能 for 零！")
else:
    print(f"计算成功, 结果 is : {result}")
finally:
    print("程序执行完毕. ")

# usingfinally子句
try:
    f = open("example.txt", "r")
    content = f.read()
    print(content)
except FileNotFoundError:
    print("file未找 to ！")
finally:
    # 无论 is 否发生exception, 都会执行这里 code
    if 'f' in locals() and not f.closed:
        f.close()
        print("file已关闭. ")

# usingwith语句 (更简洁 方式) 
try:
    with open("example.txt", "r") as f:
        content = f.read()
        print(content)
except FileNotFoundError:
    print("file未找 to ！")
# with语句会自动关闭file, 不需要finally子句

# 手动抛出exception
def divide(a, b):
    if b == 0:
        raise ZeroDivisionError("除数不能 for 零！")
    return a / b

try:
    result = divide(10, 0)
    print(f"结果 is : {result}")
except ZeroDivisionError as e:
    print(f"捕获 to exception: {e}")

# 重 new 抛出exception
def process_data(data):
    try:
        # processingdata
        if not data:
            raise ValueError("data for 空！")
        return len(data)
    except ValueError as e:
        print(f"processingdata时发生error: {e}")
        # 重 new 抛出exception
        raise

try:
    result = process_data([])
    print(f"processing结果: {result}")
except ValueError as e:
    print(f" on 层捕获 to exception: {e}")

# 自定义exceptionclass
class InvalidAgeError(Exception):
    """年龄无效exception"""
    def __init__(self, age, message="年龄无效"):
        self.age = age
        self.message = message
        super().__init__(self.message)
    
    def __str__(self):
        return f"{self.message}: {self.age}"

class NegativeAgeError(InvalidAgeError):
    """年龄 for 负exception"""
    def __init__(self, age):
        super().__init__(age, "年龄不能 for 负数")

# using自定义exception
def register_user(name, age):
    if age < 0:
        raise NegativeAgeError(age)
    elif age < 18:
        raise InvalidAgeError(age, "年龄必须满18岁")
    print(f"user {name} register成功！")

try:
    register_user("Alice", 25)
except InvalidAgeError as e:
    print(f"register失败: {e}")

try:
    register_user("Bob", 15)
except InvalidAgeError as e:
    print(f"register失败: {e}")

try:
    register_user("Charlie", -5)
except InvalidAgeError as e:
    print(f"register失败: {e}")