>>> 5/0
Traceback (most recent call last):
File "<pyshell#6>", line 1, in <module>
5/0
ZeroDivisionError: division by zero
>>> open("myfile.txt")
Traceback (most recent call last):
File "<pyshell#7>", line 1, in <module>
open("myfile.txt")
FileNotFoundError: [Errno 2] No such file or directory: 'myfile.txt'
>>> FileNotFoundError), dividing a number by zero (ZeroDivisionError), module we try to import is not found (ImportError) etc.
| EXCEPTION | DESCRIPTION |
|---|---|
| ZeroDivisionError | Raised when division or modulo by zero takes place for all numeric types. |
| Exception | Base class for all exceptions |
| StopIteration | Raised when the next() method of an iterator does not point to any object. |
| ImportError | Raised when an import statement fails. |
| KeyboardInterrupt | Raised when the user interrupts program execution, usually by pressing Ctrl+c. |
| SystemExit | Raised by the sys.exit() function. |
| StandardError | Base class for all built-in exceptions except StopIteration and SystemExit. |
| ArithmeticError | Base class for all errors that occur for numeric calculation. |
| OverflowError | Raised when a calculation exceeds maximum limit for a numeric type. |
| FloatingPointError | Raised when a floating point calculation fails. |
| TabError | Raised when indentation consists of inconsistent tabs and spaces. |
| UnicodeError | Raised when a Unicode-related encoding or decoding error occurs. |
| AssertionError | Raised in case of failure of the Assert statement. |
| AttributeError | Raised in case of failure of attribute reference or assignment. |
| EOFError | Raised when there is no input from either the raw_input() or input() function and the end of file is reached. |
| LookupError | Base class for all lookup errors. |
| IndexError | Raised when an index is not found in a sequence. |
| KeyError | Raised when the specified key is not found in the dictionary. |
| NameError | Raised when an identifier is not found in the local or global namespace. |
| UnboundLocalError | Raised when trying to access a local variable in a function or method but no value has been assigned to it. |
| IOError | Raised when an input/ output operation fails, such as the print statement or the open() function when trying to open a file that does not exist. Raised for operating system-related errors. |
| SyntaxError | Raised when there is an error in Python syntax. |
| SystemError | Raised when the interpreter finds an internal problem, but when this error is encountered the Python interpreter does not exit. |
| SystemExit | Raised when Python interpreter is quit by using the sys.exit() function. If not handled in the code, causes the interpreter to exit. |
| TypeError | Raised when an operation or function is attempted that is invalid for the specified data type. |
| ValueError | Raised when the built-in function for a data type has the valid type of arguments, but the arguments have invalid values specified. |
| RuntimeError | Raised when a generated error does not fall into any category. |
| NotImplementedError | Raised when an abstract method that needs to be implemented in an inherited class is not actually implemented. |
| EnvironmentError | Base class for all exceptions that occur outside the Python environment. |
| IndentationError | Raised when indentation is not specified properly. |
| GeneratorExit | Raise when a generator's close() method is called. |
| OSError | Raised when system operation causes system related error. |
| ReferenceError | Raised when a weak reference proxy is used to access a garbage collected referent. |
Exception in a code can also be handled. In case it is not handled, then the code is not executed further and hence execution stops when exception occurs.
The suspicious code can be handled by using the try block. Enclose the code which raises an exception inside the try block. The try block is followed except statement. It is then further followed by statements which are executed during exception and in case if exception does not occur.
try:
malicious code
except Exception-1:
execute code
except Exception-2:
execute code
....
....
except Exception-N:
execute code
else:
In case of no exception, execute the else block code. >>> try:
a=16/0
print (a)
except ArithmeticError:
print ("This statement is raising an exception " )
else:
print ("Free Time Learning")
This statement is raising an exception
>>> You can also use the same except statement to handle multiple exceptions as follows :
try:
your operations here;
......................
except(Exception1[, Exception2[,...ExceptionN]]]):
If there is any exception from the given exception list,
then execute this block.
......................
else:
If there is no exception then execute this block.In Python programming, exceptions are raised when corresponding errors occur at run time, but we can forcefully raise it using the keyword raise.
You can raise exceptions in several ways by using the raise statement. The general syntax for the raise statement is as follows :
>>> try:
a=10
print (a)
raise NameError("FTL")
except NameError as e :
print ("An exception occurred")
print (e)
10
An exception occurred
FTL
>>> The try statement in Python can have an optional finally clause. This clause is executed no matter what, and is generally used to release external resources.
The finally block is a place to put any code that must execute, whether the try-block raised an exception or not. The syntax of the try-finally statement is following :
>>> try:
a=8/0;
print ("Exception occurred")
finally:
print ("Code to be executed")
Code to be executed
Traceback (most recent call last):
File "<pyshell#54>", line 2, in <module>
a=8/0;
ZeroDivisionError: division by zero
>>>