Detailed Explanation of python Exception Catch and Remedy Example

1. Catch specific exceptions

The first qualified except statement is executed to report the error. If only an error is reported, the program will still stop.

a = 0
try:
    b = 5/a
except ZeroDivisionError:
    print('Error: a Cannot be for 0')
except ValueError:
    print('Error:  Invalid parameter passed in ')

2. Catch all exceptions

Exception after the except statement indicates that any exception type is caught.

a = 0
try:
    b = 5/a
except Exception:
    print('a Cannot be for 0')

3. Abnormal remedy

Possible exceptions are remedied after the except statement, such as manually specifying the file address when the default file address cannot be found.

a = 0
try:
    b = 5/a
except:
    b = 0

Extension of knowledge points:

Built-in hierarchy of exception classes

BaseException # Base class for all exceptions
+--SystemExit interpreter requests exit
+--KeyboardInterrupt # User interrupts execution (typically enter ^ C)
+--GeneratorExit # Generator (generator) has an exception to notify exit
+--Base class for Exception # General exceptions
+--StopIteration # Iterator has no more values
+--StopAsyncIteration # must be raised by the __anext__ () method of the asynchronous iterator object to stop the iteration
+--ArithmeticError # Base class for built-in exceptions thrown by various arithmetic errors
+--FloatingPointError # Floating-point calculation error
+--OverflowError # Numeric result too large to represent
+--ZeroDivisionError # divide (or modulo) zero (all data types)
+--AssertionError # Raised when an assert statement fails
+--AttributeError # Attribute reference or assignment failed
Raised when +--BufferError # fails to perform buffer-related operations
+--EOFError # Raised when the input () function meets the end of file condition (EOF) without reading any data
+--ImportError # Failed to import module/object
+--ModuleNotFoundError # Unable to find module or found None in sys. modules
+--Base class for exceptions thrown when a key or index used on an LookupError # map or sequence is invalid
This index is not in the +--IndexError # sequence (index)
+--This key is not in the KeyError # mapping
+--MemoryError # Memory overflow error (not fatal to Python interpreter)
+--NameError # Undeclared/initialized object (no properties)
+--UnboundLocalError # Access uninitialized local variables
+--OSError # Operating System Error, EnvironmentError, IOError, WindowsError, socket. error, select. error and mmap. error have been merged into OSError, constructor may return subclasses
The +--BlockingIOError # operation sets the blocking object (e. g. socket) to a non-blocking operation
+--ChildProcessError # Operation failed on child process
+--Base class for ConnectionError # Connection-related exceptions
+--BrokenPipeError # Attempt to write to a pipe when the other 1 end is closed or attempt to write to a socket where writing is closed
+--ConnectionAbortedError # Connection attempt aborted by peer
+--ConnectionRefusedError # Connection attempt rejected by peer
+--ConnectionResetError # Connection reset by peer
+--FileExistsError # Create an existing file or directory
+--FileNotFoundError # Request a file or directory that does not exist
+--InterruptedError # system call interrupted by input signal
+--IsADirectoryError # Request file operations on a directory (for example, os. remove ())
+--NotADirectoryError # Request directory operations on things that are not directories (e.g. os. listdir ())
+--PermissionError # attempts to run an operation without sufficient access
+--ProcessLookupError # The given process does not exist
+--TimeoutError # System functions time out at the system level
+--The weak reference created by the ReferenceError # weakref. proxy () function attempts to access an object that has been garbage collected
+--RuntimeError # Triggered when an error is detected that does not belong to any other category
+--NotImplementedError # In a user-defined base class, an abstract method requires a derived class to override the method or the class under development indicates that the actual implementation still needs to be added
+--RecursionError # Interpreter Detects Exceeding Maximum Recursive Depth
+--SyntaxError # Python syntax error
+--IndentationError # Indent error
+--TabError # Tab mixed with spaces
+--SystemError # Interpreter Found Internal Error
+--TypeError # Operation or function applied to an object of inappropriate type
+--ValueError # An operation or function receives an argument of the correct type but with an inappropriate value
+--UnicodeError # Encoding or decoding error associated with Unicode occurred
+--UnicodeDecodeError # Unicode decoding error
+--UnicodeEncodeError # Unicode encoding error
+--UnicodeTranslateError # Unicode transcoding error
+--Base class for Warning # Warnings
+--DeprecationWarning # Base class for warnings about deprecated features
+--PendingDeprecationWarning # Base class for warnings about deprecated features
+--RuntimeWarning # Base class for warnings about suspicious runtime behavior
+--SyntaxWarning # Base class for suspicious syntax warnings
+--Base class for UserWarning # User code to generate warnings
+--Base class for FutureWarning # Warnings about deprecated features
+--ImportWarning # Base class for warnings about possible errors when importing modules
+--UnicodeWarning # Base class for Unicode-related warnings
+--BytesWarning # Base class for bytes and bytearray related warnings
+--ResourceWarning # Base class for resource usage related warnings. Ignored by default warning filter.