Prof. Scott
Lecture date:  8/25/22

* examples from CS102  ->  hello world, input output, other basics 

Brief discussion of stream operators, preprocessor, namespaces


NOTE!!!  main function must always exist, just like in C!


Additional examples to show similarities with C/help with prelab:
-------------------------

-> add.cc :    variables, input output, sums
-> stat.cpp:   arrays, for loops, brief into to C++ strings
-> digits.cc:  while loops
-> sizes.cpp:  uses sizeof to determine memory required for different types (see below)

Variables
---------

We will be starting with very "C-like" programs that mix C/C++ syntax pretty intentionally.  This
may or may not be a review, but variables at this point come from a few basic "groups":

integer:  char, short, int, long, long long  (char is less than short, see sample program
real:  float, double, long double

Static arrays/aggregrate data types (struct)

Classes and objects (aggregate data types boosted with OOP principles)

Note:  Aggregate data types are contigious in memory, starting at the address of the variable.  So,
for example, for a static array of 10 ints (40 bytes on tesla), the first element is A + 0, second
element is A + 4, etc.  These "jumps" are why we use A[0], A[1], A[2], etc. as the compiler will use
the initial address (i.e, &A) for the first element, shift one element (here 4 bytes), two elements
(8), etc.  This may or may not be important in CS202 but it is something we should cover and you
should know.

Variable scope
--------------

Variables in C++ can have different scope.  They are, in short:

global :  declared outside functions, please don't use unless you have an excellent reason!

local:  declared inside { } blocks.  Note each function can have different scopes, e.g.:

int main () {

    int a = 10;
    if (a > 0) {

       Foo b;
       ...

    }

    // lots of code!

}

It may or may not matter (again) but in C++ all variables are "destroyed" when they leave scope.  As
a result, b (of type Foo) will be destroyed at the first } and a will be destroyed at the second 
(with, presumably lots of other variables declared in-between).

Remember:  all variables go "poof!" after { } blocks

Class scope -- we'll cover this later

Optional reading from text:
-------------------------

Review Figures 1.6-1.11 and associated text just in case, especially
if you have not had CS102.

First C++ program:  Section 2.2 in D&D
-	main function and output streams
-	see hello.cc in the lecture notes

Second C++ program:  Section 2.4
-	adding two numbers; sample code in lecture notes as add.cc