Python3 (入门4) 异常

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本文由 Luzhuo 编写,转发请保留该信息.
原文: http://blog.csdn.net/Rozol/article/details/69313164

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以下代码以Python3.6.1为例
Less is more!

#coding=utf-8# exception.py 异常import sys# === 捕获异常 (可灵活组合) ===def excep():    # - try except -    try:        print(ex)    except: # 捕获所有异常        print("捕获异常!")    try:        print(ex)    except: # 通过函数获取异常信息        types, value, back = sys.exc_info() # 捕获异常        sys.excepthook(types, value, back)  # 打印异常    try:        print(ex)    except NameError: # 捕获指定异常        print("捕获名字未定义异常!")    except IOError:        print("捕获IO异常!")    except:        print("捕获所有异常!")    try:        print(ex)    except (NameError, IOError) as e: # 同时捕获多个异常, 并告知异常原因        print("捕获多个异常!")        print(e)    except:        print("捕获所有异常!")    # - try except else -    try:        pass    except:        print("捕获异常!")    else: # 没有发生异常是执行该代码块        print("运行正常.")    # - try except else finally -    try:        pass    except:        print("捕获异常!")    else:        print("运行正常.")    finally: # 不管是否发生异常都执行        print("不管是否发生异常都执行")# === 自定义异常 ===# - 编写自定义异常 -class MyError(Exception): # 继承 Exception    # 重写并super构造    def __init__(self, mes = "抛出一个异常."):        Exception.__init__(self)        self.message = mes    def __str__(self):        return self.message# - 使用自定义异常 - def myerr():    try:        raise MyError("抛异常!") # 抛出异常    except MyError as e: # 接住异常        print(e)# === 断言语句 ===def assertdemo():    # 断言一般用于测试, 如果测试结果为Flase,将抛出AssertionError异常    assert 3 > 4    assert 3 > 4, "抛AssertionError异常"    assert type("string") is str# ======= 函数调用 ======if __name__ == "__main__":    excep()    myerr()    assertdemo()# ======= 函数调用 ======