python异常处理之捕获异常与抛出异常

import sys

try:
    a = int(sys.argv[1])
    b = int(sys.argv[2])
    c = a / b
    print("您输入的两个数相除的结果是：",c)
except IndexError:
    print("索引错误：运行程序时输入的参数个数不够")
except ValueError:
    print("数值错误：程序只能接受整数参数")
except ArithmeticError:
    print("算术错误")
except Exception:
    print("未知异常")

# 输出结果：
E:\myproj\crazy_python\07\7.2>python div_test.py 3 0
算术错误

import sys

try:
    a = int(sys.argv[1])
    b = int(sys.argv[2])
    c = a / b
    print("您输入的两个数相除的结果是：",c)
except (IndexError, ValueError, ArithmeticError):
    print("程序发生了数组越界、数字格式异常、算术异常之一")
except:
    print("未知异常")

# 输出结果
E:\myproj\crazy_python\07\7.2>python multi_exception_test.py 4 0
程序发生了数组越界、数字格式异常、算术异常之一

def foo():
    try:
        fis = open("a.txt")
    except Exception as e:
        print(e)
        print(e.args)
        print(e.errno)
        print(e.strerror)


foo()

# 输出结果：
[Errno 2] No such file or directory: ‘a.txt‘
(2, ‘No such file or directory‘)
2
No such file or directory

import os


def test():
    fis = None
    try:
        fis = open("a.txt")
    except OSError as e:
        print(e.strerror)
        return
        os._exit(1)
    finally:
        if fis is not None:
            try:
                fis.close()
            except OSError as ioe:
                print(ioe.strerror)
        print("执行finally里的资源回收！")


test()

# 输出结果：
No such file or directory
执行finally里的资源回收！

def test():
    try:
        return True  # 由于finally中包含return，该return语句失效
    finally:
        return False


a = test()
print(a)

# 输出结果
False