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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Exception handling in PHP

PHP has exception handling - where you can try a block of code; it it completes, that's good and normal, but if something doesn't work in the normal manner an exception is thrown, and a piece of code to mop up the problem is run, in a catch block.

I've written an example to show this ... I have a function that will return the first or second half of an input string, but if the string that's input to it is an odd number of characters long, it can't work so it throws an exception. See that code - the function and the exception handler too - [here].

Here is what I get when I run that code:

Dorothy-2:sj grahamellis$ php exp.php
Ple-ase [use] [various] excep-tions i-n [PHP]
can't cut use in 2
can't cut various in 2
can't cut PHP in 2
Dorothy-2:sj grahamellis$


Exceptions were only added to PHP quite late in the day, so you'll find that many issues with older functions are handled as errors and warnings, but modern OO based functions (and new code you write!) should use exceptions. Exception objects have a number of methods you can run on them - in the example I've given, you'll see that I've used getMessage to find out a description of the exception.

(written 2010-03-18, updated 2010-03-25)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
H999 - Additional PHP Material
  [54] PHP and natural sorting - (2004-09-19)
  [239] What and why for the epoch - (2005-03-08)
  [320] Ordnance Survey - using a 'Get a map' - (2005-05-22)
  [322] More maps - (2005-05-23)
  [337] the array returned by preg_match_all - (2005-06-06)
  [372] Time calculation in PHP - (2005-07-08)
  [468] Stand alone PHP programs - (2005-10-18)
  [483] Double Dollars in PHP - (2005-11-02)
  [493] Running a Perl script within a PHP page - (2005-11-12)
  [563] Merging pictures using PHP and GD - (2006-01-13)
  [603] PHP - setting sort order with an associative array - (2006-02-13)
  [665] PHP Image viewing application - (2006-04-01)
  [687] Presentation, Business and Persistence layers in Perl and PHP - (2006-04-17)
  [789] Hot answers in PHP - (2006-07-02)
  [806] Check your user is human. Have him retype a word in a graphic - (2006-07-17)
  [822] PHP - a team member leaves - (2006-08-04)
  [839] Reporting on the 10 largest files or 10 top scores - (2006-08-20)
  [917] Syntax checking in PHP - (2006-11-07)
  [937] Display an image from a MySQL database in a web page via PHP - (2006-11-22)
  [1010] Dates, times, clickable diarys in PHP - (2006-12-28)
  [1020] Parallel processing in PHP - (2007-01-03)
  [1053] Sorting people by name in PHP - (2007-01-26)
  [1104] Drawing dynamic graphs in PHP - (2007-03-09)
  [1194] Drawing hands on a clock face - PHP - (2007-05-19)
  [1270] PHP Standalone - keyboard to screen - (2007-07-18)
  [1389] Controlling and labelling Google maps via PHP - (2007-10-13)
  [1390] Converting from postal address to latitude / longitude - (2007-10-13)
  [1391] Ordnance Survey Grid Reference to Latitude / Longitude - (2007-10-14)
  [1451] More PHP sample and demonstration programs - (2007-12-01)
  [1485] Copyright and theft of images, bandwidth and members. - (2007-12-26)
  [1505] Script to present commonly used images - PHP - (2008-01-13)
  [1519] Flipping images on your web page - (2008-01-26)
  [1623] PHP Techniques - a workshop - (2008-04-26)
  [2073] Extra PHP Examples - (2009-03-09)
  [2215] If nothing, make it nothing. - (2009-06-02)
  [3118] Arrays of arrays - or 2D arrays. How to program tables. - (2011-01-02)
  [3210] Catchable fatal error in PHP ... How to catch, and alternative solutions such as JSON - (2011-03-22)
  [4655] Image indexer / thumbnail display scripts in PHP - (2016-02-25)


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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.

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