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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.
Wimbledon Neck

What use is the "+=" operator? Why did the language designers bother to provide it? Yet they did ...

In Perl and PHP

$number_on_bus = $number_on_bus + $goton_here;
becomes
$number_on_bus += $goton_here;

In Python

number_on_bus = number_on_bus + goton_here
becomes
number_on_bus += goton_here

In C and Java

number_on_bus = number_on_bus + goton_here;
becomes
number_on_bus += goton_here;

The += operator adds the result of evaluating the expression to the right into the variable named on the left.

The code is shorter, but there's more too it than that. It makes the code easier to maintain - it saves what we call "Wimbledon Neck" which is very appropriate for me to be writing about this week as the tennis championships are just about to start. If I write
$longvariablename = $longthingummyname + $some;
then anyone coming along to maintain the code has to take a careful look on both sides of the assignment to see whether or not the information is being saved in the same slot from which it was loaded or not; can you visualise the maintainer turning his neck to the left, to the right, to the left, to the right rather like watching a tennis volley from the side line? If the element being used is a member of an array (= list in Perl) or hash (= dictionary, = associative array) then that's all the more checking to do.

So - it may not come natural to you to code += (or -= *= /= etc) but please do so ... you're making life easier for those who follow behind!
(written 2005-06-20, updated 2006-06-05)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Y103 - Python - Conditionals and Loops
  [299] What - no switch or case statement? - (2005-05-03)
  [657] The ternary operator in Python - (2006-03-25)
  [668] Python - block insets help with documentation - (2006-04-04)
  [788] New - Conditional expressions in Python 2.5 - (2006-07-01)
  [835] Python - when to use the in operator - (2006-08-16)
  [909] Python is like a narrowboat - (2006-10-30)
  [1201] No switch in Python - (2007-05-23)
  [1477] Decisions - small ones, or big ones? - (2007-12-18)
  [1661] Equality, sameness and identity - Python - (2008-05-31)
  [1696] Saying NOT in Perl, PHP, Python, Lua ... - (2008-07-04)
  [2778] Learning to program in Python 2 ... and / or in Python 3 - (2010-05-24)
  [2899] Groupsave tickets - 3 or 4 train tickets for the price of 2 - (2010-08-02)
  [3083] Python - fresh examples from recent courses - (2010-12-11)
  [3200] How a for loop works Java, Perl and other languages - (2011-03-12)
  [3397] Does a for loop evaluate its end condition once, or on every iteration? - (2011-08-18)
  [3439] Python for loops - applying a temporary second name to the same object - (2011-09-14)
  [3558] Python or Lua - which should I use / learn? - (2011-12-21)
  [3620] Finding the total, average, minimum and maximum in a program - (2012-02-22)
  [3762] Learning to program - the if statement. Python. - (2012-06-12)
  [3895] Flowchart to program - learning to program with Well House - (2012-10-14)
  [4092] Identity in Python - (2013-05-17)
  [4210] If elif elif elif - multiway selection in Python - (2013-11-16)
  [4322] Learning to Program - the conditional statement (if) - (2014-11-21)
  [4323] Learning to program - Loop statements such as while - (2014-11-22)
  [4402] Finding sum, minimum, maximum and average in Python (and Ruby) - (2015-01-19)
  [4541] Setting up and tearing down with the Python with keyword - (2015-10-16)
  [4545] Method, Class, Module, Package - how to they relate in Python? - (2015-10-17)
  [4713] Equality (in Python) - (2016-10-30)
  [4723] Conditional operators in Python - (2016-11-05)

P204 - Perl - Conditionals and Loops
  [930] -> , >= and => in Perl - (2006-11-18)
  [1191] Smart English Output - via PHP and Perl ? : operator - (2007-05-18)
  [1468] Lexical v Arithemetic testing, Bash and Perl - (2007-12-11)
  [1607] Learning to program in Perl - (2008-04-11)
  [1727] Equality and looks like tests - Perl - (2008-07-29)
  [2351] Ternary operators alternatives - Perl and Lua lazy operators - (2009-08-12)
  [2550] Do not copy and paste code - there are much better ways - (2009-12-26)
  [2711] For loop - checked once, or evety time? Ruby v Perl comparison and contrast - (2010-04-07)
  [2832] Are you learning Perl? Some more examples for you! - (2010-06-27)
  [3004] Increment operators for counting - Perl, PHP, C and others - (2010-10-18)
  [4031] Showing what programming errors look like - web site pitfall - (2013-03-06)

J704 - Java - Loops and Conditional Statements
  [1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
  [1582] Ruby, C, Java and more - getting out of loops - (2008-03-19)
  [2734] for and foreach in Java - (2010-04-22)
  [3038] Setting up individual variables, and arrays, in Java - some commented examples - (2010-11-09)
  [4346] A behaviour driven example of writing a Java program - (2014-12-09)
  [4427] Java example - for loop and conditionals from course exercise - (2015-02-16)

H104 - PHP - Control Statements
  [340] Code and code maintainance efficiency - (2005-06-08)
  [406] Assignment, equality and identity in PHP - (2005-08-08)
  [421] Don't repeat code - use loops or functions - (2005-08-21)
  [863] Double and Triple equals operator in PHP - (2006-09-12)
  [962] Breaking a loop - Ruby and other languages - (2006-12-03)
  [1199] Testing for one of a list of values. - (2007-05-22)
  [1825] Question Mark - Colon operator (Perl and PHP) - (2008-10-08)
  [2304] Extracting real data from an exported file in PHP or Perl - (2009-07-25)
  [2912] Predictions for the seagull population - (2010-08-09)
  [3914] While, for, foreach or something else to loop. - (2012-11-06)

C203 - C and C based languages - Conditionals and Loops
  [2002] New C Examples - pointers, realloc, structs and more - (2009-01-20)
  [2570] Function Prototypes in C - (2010-01-11)
  [3121] New year, new C Course - (2011-01-05)
  [3243] Breaking the running sequence - an introduction to conditional statements and loops - (2011-04-11)
  [3384] Loops - a comparison of goto, while and for - (2011-08-10)
  [4337] Learning to program sample program - past its prime, but still useful - (2014-12-02)


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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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