Python basis ⑧: Exception Handling

1, the common abnormal

1) In addition to the operational 0 --ZeroDivisionError
2) can not find the file readable --FileNotFoundError
. 3) the value of the error --ValueError
. 4) indexing error --IndexError
. 5) type error --TypeError
. 6) the error variable name --NameError

2, exception handling

. 1) try_except
  ① single branch

x = 10
y = 0
try:
	z = x/y
except ZeroDivisionError:
	print("0不能作除数")

  ② multi-branch

ls = []
d = {"name":"LC"}
try:
	d["age"]
except NameError:
	print("变量名不存在")
except IndexError:
	print("索引超出界限")
except KeyError:
	print("键不存在")

  ③ abnormal Universal Exception

ls = []
d = {"name":"LC"}
try:
	d["age"]
except Exception:
	print("出错了")

  ④ capture value as abnormal

ls = []
d = {"name":"LC"}
try:
	y = m
	d["age"]
except Exception as e:  # 获取错误的值
	print(e)

2）try_except_else

try:
	with open("try.txt") as f:
		text = f.read()
except FileNotFoundError:
	print("找不到文件")
else:
	print("找到了")

3) try_except_finally: regardless of whether the try block execution, finally finally will be executed

ls = []
d = {"name":"LC"}
try:
	y = x
	ls[3]
	d["age"]
except Exception as e:  # 获取错误的值
	print(e)
finally:
	print("执行finally")