Python特殊字符异常处理示例详解

1 / 0
# ZeroDivisionError: division by zero
'2' + 2
# TypeError: can only concatenate str (not "int") to str
open('file.txt')
# FileNotFoundError

BaseException
  └── Exception

try:
    可能出错的代码
except 异常类型:
    出错后的处理代码

try:
    x = 10 / 0
except ZeroDivisionError:
    print("除数不能为0！")

try:
    print(count)
    arr = [1,2,3]
    print(arr[5])
except NameError as e:
    print("变量未定义:", e)
except IndexError as e:
    print("索引越界:", e)

try:
    ...
except Exception as e:
    print("发生异常:", e)

try:
    x = 10 / 2
except ZeroDivisionError:
    print("错误")
else:
    print("没有异常时执行")

try:
    f = open("test.txt")
except:
    print("出错")
finally:
    print("无论如何都会执行")

try:
    ...
except:
    ...
else:
    ...
finally:
    ...

age = 15
if age < 18:
    raise ValueError("年龄必须大于18岁")

assert age >= 18, "年龄必须>=18"

def func1():
    return 10 / 0
def func2():
    func1()
try:
    func2()
except ZeroDivisionError:
    print("已捕获异常")

class AgeError(Exception):
    pass
age = 16
if age < 18:
    raise AgeError("未满18岁！")

file = open("a.txt")
...
file.close()

with open("a.txt") as f:
    print(f.read())

class MyOpen:
    def __enter__(self):
        print("进入")
    def __exit__(self, type, val, tb):
        print("退出")