Strings		Variables		Lists		Tuples		Dictionary
Control		Function		Files		Exceptions
OOP		Algorithm		Data Structure		back

---

Handling Exceptions || file and exception

The try block

lets you test a block of code for errors.

The except block

lets you handle the error.

The else block

lets you execute code when there is no error.

The finally block

lets you execute code, regardless of the result of the try- and except blocks.

Example

• open a file without write permission

  # 
  try:
   fh = open("testfile", "r")
   fh.write("My test file for exception handling!!")
  except IOError:
   print "Error: can\'t find file or read data"
  else:
   print "Written content in the file successfully"
  

try:
   fh = open("testfile", "w")
   try:
      fh.write("My test file for exception handling!!")
   finally:
      print "Going to close the file"
      fh.close()
except IOError:
   print "Error: can\'t find file or read data"

Handling Exceptions || def/program and exception

try:
    value = int(input("Enter a number between 1 and 10: "))
    #try block handles exceptions (getting input from the user)
except ValueError:
    # except block looks for a specific exception: ValueError.
    print("You must type a number between 1 and 10!") 
else:
    #else block - executed when try block doesn’t generate an exception (is successful). 
    if (Value > 0) and (Value <= 10): 
        print("You entered: ", value)
    else:
        print("Wait, wat? You entered the wrong digits!")

try:
    Value1 = int(input("Type the first number: ")) 
    Value2 = int(input("Type the second number: ")) 
    Output = Value1 / Value2
except ValueError:
    print("You must type a whole number!")
except KeyboardInterrupt: 
    print("You pressed Ctrl+C!")
except ArithmeticError:
    print("An undefined math error occurred.")
except ZeroDivisionError: 
    print("Attempted to divide by zero!")
else:
    print(Output)

• this will save an IndexError exception in the variable err
• any other exceptoion in the variable other

short_list = [1,2,3]
while True:
   value = input('Position [q to quit]?')
   if value == 'q':
      break
   try:
      position = int(value)
      print(short_list[position])
   except IndexError as err:
      print('Bad Index', position)
   except Exception as other:
      print('Something else broke: ', other)

for more visuality - maybe I should put it in a def and doc string?

Exception	Description
ArithmeticError	Raised when an error occurs in numeric calculations
AssertionError	Raised when an assert statement fails
AttributeError	Raised when attribute reference or assignment fails
Exception	Base class for all exceptions
EOFError	Raised when the input() method hits an “end of file” condition (EOF)
FloatingPointError	Raised when a floating point calculation fails
GeneratorExit	Raised when a generator is closed (with the close() method)
ImportError	Raised when an imported module does not exist
IndentationError	Raised when indentation is not correct
IndexError	Raised when an index of a sequence does not exist
KeyError	Raised when a key does not exist in a dictionary
KeyboardInterrupt	Raised when the user presses Ctrl+c, Ctrl+z or Delete
LookupError	Raised when errors raised cant be found
MemoryError	Raised when a program runs out of memory
NameError	Raised when a variable does not exist
NotImplementedError	Raised when an abstract method requires an inherited class to override the method
OSError	Raised when a system related operation causes an error
OverflowError	Raised when the result of a numeric calculation is too large
ReferenceError	Raised when a weak reference object does not exist
RuntimeError	Raised when an error occurs that do not belong to any specific exceptions
StopIteration	Raised when the next() method of an iterator has no further values
SyntaxError	Raised when a syntax error occurs
TabError	Raised when indentation consists of tabs or spaces
SystemError	Raised when a system error occurs
SystemExit	Raised when the sys.exit() function is called
TypeError	Raised when two different types are combined
UnboundLocalError	Raised when a local variable is referenced before assignment
UnicodeError	Raised when a unicode problem occurs
UnicodeEncodeError	Raised when a unicode encoding problem occurs
UnicodeDecodeError	Raised when a unicode decoding problem occurs
UnicodeTranslateError	Raised when a unicode translation problem occurs
ValueError	Raised when there is a wrong value in a specified data type
ZeroDivisionError	Raised when the second operator in a division is zero