O'Reilly logo

Python: Essential Reference, Third Edition by David Beazley

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Exceptions

If an error occurs in your program, an exception is raised and an error message such as the following appears:

Traceback (innermost last):
 File "<interactive input>", line 42, in foo.py
NameError: a

The error message indicates the type of error that occurred, along with its location. Normally, errors cause a program to terminate. However, you can catch and handle exceptions using the try and except statements, like this:

try:
    f = open("file.txt","r")
except IOError, e:
    print e

If an IOError occurs, details concerning the cause of the error are placed in e and control passes to the code in the except block. If some other kind of exception is raised, it’s passed to the enclosing code block (if any). If no errors occur, the code in ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required