Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
 
Python and Tcl - public course schedule [here]
Private courses on your site - see [here]
Please ask about maintenance training for Perl, PHP, Lua, etc
 
Server under maintenance; some slow running (1)
Exceptions in Python

Rather than having to check ahead of time for every possible error, Python provides an exception handling capability too. Simply try to perform you action, and define what's to be done in an except block if the action you want can't be completed.

Here's an example in which we (try to) read an integer value from the user. If our user types a value that's not an integer, the exception is caught and the prompt repeated


def gnum(prompt):
while 1:
try:
rv = int(input(prompt+": "))
break
except:
print "eh?"
return rv

first = gnum("First number")
second = gnum("Second number")
print "Sum is "+str(first+second)


By the way - note the use of a named block of code (a function) to avoid the need to repeat code. Good programming practise!
(written 2005-07-17, updated 2006-06-05)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Y109 - Python - Exceptions
  [4444] Elements of an exception in Python - try, except, else, finally - (2015-02-28)
  [4161] Python varables - checking existance, and call by name or by value? - (2013-08-27)
  [4029] Exception, Lambda, Generator, Slice, Dict - examples in one Python program - (2013-03-04)
  [3930] Reporting the full stack trace when you catch a Python exception - (2012-11-22)
  [3913] How many times ... has this loco headed west through Tenby? - Python exceptions - (2012-11-05)
  [3664] Error checking in a Python program - making your program robust via exceptions - (2012-03-22)
  [3441] Pressing ^C in a Python program. Also Progress Bar. - (2011-09-15)
  [3433] Exceptions - a fail-safe way of trapping things that may go wrong - (2011-09-11)
  [3177] Insurance against any errors - Volcanoes and Python - (2011-02-19)
  [2998] Using an exception to initialise a static variable in a Python function / method - (2010-10-13)
  [2994] Python - some common questions answered in code examples - (2010-10-10)
  [2622] Handling unusual and error conditions - exceptions - (2010-02-03)
  [2408] Robust user input (exception handling) example in Python - (2009-09-17)
  [2368] Python - fresh examples of all the fundamentals - (2009-08-20)
  [2281] Python - using exceptions to set a fallback - (2009-07-12)
  [2018] UnboundLocalError - Python Message - (2009-01-31)
  [1236] Trying things in Python - (2007-06-18)
  [1042] Nested exceptions in Python - (2007-01-18)


Back to
Bridging to the customer requirement
Previous and next
or
Horse's mouth home
Forward to
Central London Courses - Perl, PHP, Python, Tcl, MySQL
Some other Articles
Feast or famine
Managing conflict and disappointment
Overloading of operators on standard objects in Python
Central London Courses - Perl, PHP, Python, Tcl, MySQL
Exceptions in Python
Bridging to the customer requirement
Getting the lighting right
A word of admiration for the London cabbie
A Strengthened City
What brings people to my web site?
4759 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page


This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2019: 404 The Spa • Melksham, Wiltshire • United Kingdom • SN12 6QL
PH: 01225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/381_Exce ... ython.html • PAGE BUILT: Sat May 27 16:49:10 2017 • BUILD SYSTEM: WomanWithCat