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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Left shift operator on an output stream object - C++

When explaining "Hello World" in C++ (see here), delegates who are already familiar with programming in other languages pick up on the line
  cout << "Welcome - and enjoy your C++ course" << endl;
and ask for an explanation.

Yes - it is a bit different, isn't it?

The explanation and a full understanding come during the course though, and not necessarily at the early stage. But here goes:

The << operator is described (in C++ documentation) as the left shift operator, and indeed when used on an int data type, it takes the bit pattern that defines the integer and shifts it to the left by the number of bits given - for example:
  int value = 13;
  value = value << 2;

would take the internal format of the integer 13 (1101) and shift it 2 left (110100) - or 52 in decimal.

cout is an output stream object - and the concept of doing a "left shift" on a stream is a nonsense idea, so the authors of C++ used the operator which was going "spare" for something else - to send the contents of the expression to the right of the << to the stream named on its left.

The << operation on an output stream returns a reference to the stream, thus allowing further << operations to be concatanated onto the first one - allowing for a series out outputs in a single expression.

Full example of shifting in C++ [here] ... note that for an input stream (our example uses cin, the >> operator (right shift) is also overloaded, indicating that data from the input stream is sent to the named variable.
(written 2015-10-30)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
C231 - C and C based languages - Introduction to C++
  [317] Programming languages - a comparison - (2005-05-20)
  [318] Choosing a theme - (2005-05-20)
  [336] Targetted Advertising - (2005-06-05)
  [928] C++ and Perl - why did they do it THAT way? - (2006-11-16)
  [2004] Variable Scope in C++ - (2009-01-22)
  [2169] When should I use OO techniques? - (2009-05-11)
  [2845] Objects and Inheritance in C++ - an easy start - (2010-07-01)
  [3052] Getting your C++ program to run - (2010-11-15)
  [3053] Make - automating the commands for building and installing - (2010-11-16)
  [3069] Strings, Garbage Collection and Variable Scope in C++ - (2010-11-25)
  [3250] C++ - how we teach the language and the concepts behind the language - (2011-04-17)
  [4466] Moving from C to C++ - Structured to Object Oriented - a lesson for engineers - (2015-03-28)
  [4561] Hello World in C++ - a first program, with the process explained - (2015-10-30)

C235 - C and C based languages - I/O in C++
  [1478] Some new C programming examples - files, structs, unions etc - (2007-12-19)
  [1675] Comparing Objects in C++ - (2008-06-13)
  [3124] C++ - putting the language elements together into a program - (2011-01-08)
  [3252] C++ - unknown array size, unknown object type. Help! - (2011-04-17)
  [3390] Printing objects in C++ - (2011-08-13)
  [3807] Reading (and writing) files in C++ - (2012-07-18)
  [3810] Reading files, and using factories to create vectors of objects from the data in C++ - (2012-07-21)
  [4563] Formatting and outputting your own classes in C++ - (2015-10-30)


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Some other Articles
C - why is slow to write and debug) but fast to run?
Allocation of memory for objects in C++ - Stack v Heap
Perl, PHP, Python, Lua, Tcl, C++, Ruby - final public courses for 2015
Left shift operator on an output stream object - C++
Variables, Pointers and References - C and C++
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++
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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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