python try exception handling (most complete ever)

In the program when there is a bug generally will not display the error message to the user, but the reality of a hint of the page, in layman's terms, is not to let the user see the rhubarb page!!!!

Sometimes when we write a program, there are errors or exceptions that cause the program to terminate .

To handle exceptions, we use try... .except

Put statements where errors may occur in the try module and use except to handle exceptions.

except can handle a specialized exception or a set of exceptions in parentheses.

If no exception is specified after except, all exceptions are handled by default.

For every try, there must be at least one except

Among python's exceptions, there is a catch-all exception: Exception, who can catch any exception

s1 = 'hello'
try:
  int(s1)
except Exception,e:
  print e

The program needs to take into account the possibility of multiple exceptions in the try block, which can be written like this:

s1 = 'hello'
try:
  int(s1)
except IndexError,e:
  print e
except KeyError,e:
  print e
except ValueError,e:
  print e

Simple and complex structures of exceptions

 try:
pass
except Exception as e: #python2 can also be written like this: except Exception,e
pass

full set of real columns

try:
  # Main code block
  pass
except KeyError,e:
  # Execute the block on an exception
  pass
else:
  # After the main code block is executed, execute the block
  pass
finally:
  # Finalize the execution of the block, regardless of exceptions
  pass

Define the special alert exception first, and then define the Exception to ensure that the program runs properly.

first the special, then the universal

s1 = 'hello'
try:
  int(s1)
except KeyError,e:
  print 'Key error'
except IndexError,e:
  print 'Indexing error'
except Exception, e:
  print 'Error'

active trigger exception

raise Exception('messages') can be customized.

a=2
if a > 1:
  raise ValueError('Value greater than 1')

raise Trigger Exception

try:
  raise Exception('Wrong...')
except Exception,e:
  print e

Customized exceptions

 class WupeiqiException(Exception):
 
  def __init__(self, msg):
     = msg
 
  def __str__(self):
    return 
 
try:
  raise WupeiqiException('My anomaly')
except WupeiqiException,e:
  print e

All of python's standard exception classes:

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