[basic 7] - exceptions, capture and customize exceptions

abnormal

Exceptions will cause the program to terminate

One 、 Common abnormal

SyntaxError Grammar mistakes
NameError Wrong variable name
IndentationError The indentation error
ModuleNotFoundError Third party package not installed
FileNotFoundError File not found
AttributeError: 'int' object has no attribute 'eat' Object does not have a property or method
IndexError: list index out of range Index out of bounds
ZeroDivisionError: division by zero The divisor cannot be zero 0

Two 、 Capture exception

When an exception occurs , Get abnormal information and deal with it accordingly , Avoid program crashes

• only Can catch runtime exceptions , If the code itself does not work properly, it cannot be captured

try···except

try:
Code with possible exception
except Exception as e:
Code executed when an exception occurs

lista=[15,15,45,8,0,98,8,14]

for s in lista:
    try:
        r=10/s
        print(r)
    except Exception as e:#Exception  The type of error captured  e Save the specific error content 
        print(" There is an error ：",e)

0.6666666666666666
0.6666666666666666
0.2222222222222222
1.25
There is an error ： division by zero
0.10204081632653061
1.25
0.7142857142857143

else and finally sentence

try:
Code with possible exception
except Exception as e:
Code executed when an exception occurs
else:
Code executed when there is no exception
finally
Whether or not there is an exception , It will be carried out ( Log , close resource )

lista=[15,15,45,8,0,98,8,14]

for s in lista:
    try:
        r=10/s
        print(r)
    except Exception as e:#Exception  The type of error captured  e Save the specific error content 
        print(" There is an error ：",e)
    else:
        print(" normal ！")
    finally:
        print("---- completion of enforcement ！")

0.6666666666666666
normal ！
---- completion of enforcement ！
0.6666666666666666
normal ！
---- completion of enforcement ！
0.2222222222222222
normal ！
---- completion of enforcement ！
1.25
normal ！
---- completion of enforcement ！
There is an error ： division by zero
---- completion of enforcement ！
0.10204081632653061
normal ！
---- completion of enforcement ！
1.25
normal ！
---- completion of enforcement ！
0.7142857142857143
normal ！
---- completion of enforcement ！

3、 ... and 、 Custom exception

Create an exception object

exp=Exception(" Gender can only be male or female ！")# Create an exception object 
sex=input(" Please enter your gender （ male 、 Woman ）")
if sex==" male "or sex==" Woman ":
    print(" Gender you entered ：",sex)
else:
    print(" The gender you entered is wrong ！")
    raise exp

Please enter your gender （ male 、 Woman ）wu
The gender you entered is wrong ！
Exception: Gender can only be male or female ！