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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.
When do I use the this keyword in C++?

Question: When do I use the this keyword in C++?

Answer: When I expliciy need (or want) to refer to a member variable or object within the current object.

Example:

   class Transport{
      public:
         Transport(int);
         int nSeats;
      };


I could define my constructor as follows:
   Transport::Transport(int nS) { nSeats = nS; }
But that means that I've had to come up with a second variable name for "number of seats" and may lead to confusion in future code work where I have to remember which particular word I used where. The Eskimos may have 450 different words for "snow", but a program is far more followable and maintanable if we have just one. But writing
   Transport::Transport(int nSeats) { nSeats = nSeats; }
isn't going to work, because the parameter nSeats masks the object member, and the assignment just overwrites a variable with itself, and the object member does not get set. The solution is "this" to explicitly refer to the object member:
   Transport::Transport(int nSeats) { this->nSeats = nSeats; }

From yesterday's C++ - sample code [here] showing this, vector, iand examples of factory, inherrited constructor, file input, and a tokeniser.
(written 2015-10-29)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
C234 - C and C based languages - Further C++ Object Oriented features
  [801] Simple polymorphism example - C++ - (2006-07-14)
  [802] undefined reference to typeinfo - C++ error message - (2006-07-15)
  [831] Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13)
  [1159] It can take more that one plus one to get two. - (2007-04-22)
  [1819] Calling base class constructors - (2008-10-03)
  [2004] Variable Scope in C++ - (2009-01-22)
  [2005] Variables and pointers and references - C and C++ - (2009-01-23)
  [2576] What does const mean? C and C++ - (2010-01-15)
  [2673] Multiple Inheritance in C++ - a complete example - (2010-03-12)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2849] What are C++ references? Why use them? - (2010-07-02)
  [3057] Lots of things to do with and within a C++ class - (2010-11-16)
  [3069] Strings, Garbage Collection and Variable Scope in C++ - (2010-11-25)
  [3124] C++ - putting the language elements together into a program - (2011-01-08)
  [3238] Bradshaw, Ben and Bill. And some C and C++ pointers and references too. - (2011-04-09)
  [3430] Sigils - the characters on the start of variable names in Perl, Ruby and Fortran - (2011-09-10)
  [3509] Operator Overloading, Exceptions, Pointers, References and Templates in C++ - new examples from our courses - (2011-11-06)
  [3982] Using a vector within an object - C++ - (2013-01-19)
  [4366] Changing what operators do on objects - a comparison across different programming languages - (2014-12-26)
  [4377] Designing a base class and subclasses, and their extension, in C++ - (2015-01-01)

C239 - C and C based languages - Putting it all together
  [836] Build on what you already have with OO - (2006-08-17)
  [925] C++ - just beyond the basics. More you can do - (2006-11-14)
  [945] Code quality counts - (2006-11-26)
  [1181] Good Programming practise - where to initialise variables - (2007-05-09)
  [2646] Compile but do not run PHP - syntax check only - (2010-02-22)
  [2674] Make and makefiles - a commented example to help you learn - (2010-03-12)
  [2851] Further C++ material - view new or old - (2010-07-04)
  [3067] Using C and C++ functions in the same program - how to do it - (2010-11-24)
  [3252] C++ - unknown array size, unknown object type. Help! - (2011-04-17)
  [3810] Reading files, and using factories to create vectors of objects from the data in C++ - (2012-07-21)
  [4326] Learning to program - comments, documentation and test code - (2014-11-22)
  [4374] Test driven development, and class design, from first principles (using C++) - (2014-12-30)

C233 - C and C based languages - OO in C++ - beyond the basics
  [798] References and Pointers in C++ - (2006-07-10)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1572] C - structs and unions, C++ classes and polymorphism - (2008-03-13)
  [1674] What a lot of files! (C++ / Polymorphism demo) - (2008-06-12)
  [2577] Complete teaching example - C++, inheritance, polymorphism - (2010-01-15)
  [2845] Objects and Inheritance in C++ - an easy start - (2010-07-01)
  [3056] C++ - a complete example with polymorphism, and how to split it into project files - (2010-11-16)
  [3123] C++ objects - some short, single file demonstrations - (2011-01-07)
  [3142] Private and Public - and things between - (2011-01-22)
  [3244] C and C++ - preprocess, compile, load, run - what each step is for - (2011-04-12)
  [3251] C++ - objects that are based on other objects, saving coding and adding robustness - (2011-04-17)
  [3508] Destructor methods in C++ - a primer - (2011-11-05)
  [3811] Associated Classes - using objects of one class within another - (2012-07-21)
  [3979] Extended and Associated objects - what is the difference - C++ example - (2013-01-18)
  [4356] Object factories in C++, Python, PHP and Perl - (2014-12-19)
  [4375] Final examples for 2014 - and a look at our 2015 training course options - (2014-12-31)
  [4560] Variables, Pointers and References - C and C++ - (2015-10-29)


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Variables, Pointers and References - C and C++
Some other Articles
Formatting and outputting your own classes in C++
Left shift operator on an output stream object - C++
Hello World in C++ - a first program, with the process explained
When do I use the this keyword in C++?
Well House Consultants - Python courses / what's special.
Function prototype - what they are and why you should use them - C and C++
Strings in C - strncmp strncpy and friends
Preprocessor directives in C and C++ - what they mean
Passing information into functions in C - by name, by value
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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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