. 04 C++ elements and Case study
. Previous -- First Program
.See ./03.html
.Open Prepare -- C++ Elements
. 2.6 Arithmetic
. Fig 2.9 Arithmetic Operators
You need to know about "+", "-", "*", "/" and "%".  But they are fairly straightforward, except
for the '%' modulus operator and integer division.  By the way.... C++ has a lot more
operators: "!", "^', "&", "&&", "|", "||", ... which we will discover later.

Note: "^" is not exponentiation!

Note: don't forget that 3/6 is 0 in C++, but 3.0/6.0 is 0.5.  Changing from "int" division
to "double" division, often fixes a bug.
. Fig 2.10 Precedence of operators
Vital.  If you haven't learned these in algebra ------- put them on your cheat sheet
or memorize the British mnemonic
BODMAS::="Brackets, Division, Multiplication, Addition, Subtraction".

. 2.7 Decision Making: Equality and Relational Operators 
Look out for the traps: "==", ">=", "<=", ...
. Figure 2.13 -- ifs and conditions
Using some advanced features of C++ (Classes 8 through to 13) this program can be much improved:-(

. 2.8 Software Engineering Case Study: Examining the ATM Requirements Specification 
Notice that that the screen images and usage scenarios (lists of actions)
are very important and proceed the use case diagram.  Beware of
drawing a use case diagram before you have written down who you users are and
what they will be doing with your software.

. 2.9 Wrap-Up
. Summary -- worth looking at
. Self Review Exercises you have time
Pages 71-72 exercises 2.1,2.2,2.3.
Pages 76-77 exercises 2.4, 2.5, 2.6
.Close Prepare -- C++ Elements
. Deliver -- Question and Project 2
Project 2:  a use case describing a typical user and how they get something
of value out of your program.  Not a diagram but some text:
.As_is Programmer: RJB
.As_is Project: CWeb
.As_is User: Jo Coyote is taking CS201.
.As_is Jo can log in, input a simple C++ program, compile it, and test it
.As_is from off campus using a standard web browser.
This is called an informal "use case".

. Exercises probably from 2.14-2.26
. Quiz 1
Not completely different from the stuff in exercises 2.1 to 2.26.
. Next -- Objects and Classes
.See ./05.html