. 12 Other Control Structures -- do-while + switch + break and continue
You have to know these to be competent, but I reccommend that you don't use them.
. Previous -- the for statement
.See ./11.html
.Open Prepare
. 5.5 do...while Repetition Statement
Examples:
.See ./dowhile.cpp
(buggy),
.See ./dowhile2.cpp
(runs but a joke).

. 5.6 switch Multiple-Selection Statement
. 5.7 break and continue Statements
.Close Prepare
. Deliver -- Question and P6
.Open Questions with Answers
. Explain == and =
The double equals is a test to see if the two sides are equal.  It mostly appears
inside ifs, whiles, fors, etc.   It returns a bool value of either `true` or `false`
.As_is 		if(answer=='y')

The single equals sign is used to assign a new value to a variable.  Here
is the format for an assignment statement:
.As_is 		variable = expression ;
It evaluates the expression and puts the result into the variable.

It is quite legal to put an assignment inside any other statement because it
returns a value -- the value that was assigned to the variable.  So you can find things
like this
.As_is 		sum=sumsquares=0;
and it will compile and assign the 0 to two variables (useful!).  But also this
.As_is 		if ( a = 24 )
which will compile, assign 24 to `a` and return a non-zero value of 24 which the `if` will
interpret as true.  This is often a bug..... but some master C++ programmers use an
"=" in a condition to great effect.  There is an example in
.See ./lab07/

. How long a chain of else-if can you have
As long as you like.
. Why use setprecision
We use this to make the output has a certain number of decimal places.  For example money
usually has two deimal places, only.
. Example setw
setw(n)::iomanip="Set width of next output to `n`".

. What is ASCII
ASCII::=http://cse.csusb.edu/dick/samples/comp.text.ASCII.html

. What is type char
This is a "golden oldy" of computing.
C++ inherits a special data type that is like an integer but only big enough to store
a character -- in most cases an ASCII character.  A character (roughly) is what is sent to the
computer when you tap a key once.   The constant characters are shown in a program
with single quotes, by the way.  You can do arithmetic on `char`s.  You can assign and
test `char`s.  They often appear in a switch like the next one.
. Give an example of a switch
.As_is 		switch( answer )
.As_is 		{
.As_is 		  case 'Y':
.As_is 		  case 'y': //handle Yes....
.As_is 		  break;
.As_is 		  case 'N':
.As_is 		  case 'n': //handle No...
.As_is 		  break;
.As_is 		  default: //handle unexpected answer
.As_is		}
. When should we use the default case
All good switches have a default case.
. What is cin.get()
This is an expression that sends the "get" message to the `cin` object.  When `cin`
has `get()` called it takes the next character from the input and returns it as a value
of `cin.get()`.  BUT if there is no next character then it returns $EOF.
. Explain EOF and character input
EOF::acronym="End Of File", term used thru out computing.

C++ has roots in the time before standard character codes -- when each
company had their own way of signaling end of file.  This was when
C was young and didn't know that it would give birth to C++.
The C people had a clever idea.  Not intuitive -- clever.
They decide that when you tried to read a character from an input stream
you would be given an int value.  If this value represented a character
(typically in range 0 to 255 of ASCII) all was well.  If the stream
was ended then the value '-1' (negative one) would be returned instead.
.As_is 		int input=cin.get();
.As_is 		if(input!= -1)...

In the input/output libraries they defined a constant called `EOF`
equal to minus 1.  This made code a little easier to read.
.As_is 		int input=cin.get();
.As_is 		if(input!=EOF)...

When the standard was written it was decreeed that EOF could be any
int that was not in the character range.  So, we dare not write "-1"
when we should have written "EOF".  Some new library may use -42!

. Why is grade or cin.get() an int
There was and is no common end of file char.

If character input is put in a "char" you can not determine if
the end of file has arrived.   It always looks like a char. By using
an int we have at least one extra value we can use to signal end of file.

. Explain line 60 on page 209
.As_is 		while ( ( grade = cin.get() ) != EOF )
This is a common cliche -- it does these things:
.List
	Get the next character from cin (if any).
	If there was a character put its code in grade.
If not, put EOF in grade.
	Test if grade has been set to EOF or is it a character
	If not EOF enter the loop.
Else jump to the end of the loop.
.Close.List
This is what Lewis Carrol would call a "portmanteu"  it combines
several functions into one statement.  This is not normally a good
idea, but this one has been used in thousands of programs and
so you can trust it.

Meanwhile: keep a copy of a loop like this so you can copy it into
your own programs.  For example:
.See ./kitten.cpp
, the little 'copycat' command.

. Is there another way to input characters
Yes.  There is a different way to get a character from an input
stream:
.As_is 		char c;
.As_is 		while( cin.get(c) ) ...
Notice:  we input the character (if any) into a char, and the
command itself returns True if OK and false if not.  To see how
this works go to
.See ./copy.cpp
, a version of `kitten`.

.Close
. Exercises
. Quiz 5
. Next -- Logic and Conditions
.See ./13.html