Pascal Programming: Week 7 Notes       


	Assignment #1 and #2

Read Chapter 9, Chapter 13 pg.515-537, Chapter 14 pg. 559-565

	Team discussion:  System Breakdown and Unit Development

Ordinal Types
In Pascal, a type whose values are specified by a list is called an ORDINAL 
type; e.g. Integer, Boolean and Character where the list of values for these types are system defined.

Ordering and use of relational operators
Ascii ordering - Uppercase precedes lowercase characters.

Functions:  Pred() - returns predecessor
		   Succ() - returns successor
		   Ord() - returns ordinal position in list for the "char" given
		   Chr() - returns "char" value of the ordinal (inverse of Ord() )

Enumerated Types - User defined list of values of an Ordinal type.
	A list of identifiers that are the "values" for that variable.


Subrange Types
A new type whose values are a subrange of the values of some existing ordinal
type.
The "R" Compiler Directive for range checking.
Turbo pascal will not always give an error message if your program assigns an illegal value to a variable of a subrange type so {&R+}

e.g.
Type
	Grade = 'A' .. 'F';


Random Number Generators
Pseudo random number generators
System RNG:  random() 
	Range of values
	Initializing the RNG - Random Seed and Randomize
Pg. 559-565


More on ARRAYS
No dynamic array lengths in Turbo Pascal
Partially filled arrays require special care to prevent OVERFLOW errors
Need to know where the array ends
Need to define the array as the largest size you might need.
Array expansion allowed by changing the bounds of the array
Empty array handling must be done.
	e.g. the code on pg. 343
Must initialize the array index AND the array contents.
Storage Issues: (arrays and  parameter passing)   pg.347

Procedure Recursion 
Pgs. 515-537
Example:  Procedure to check for valid input on account number

Designing for recursion.
Tower of Hanoi Example.

- Recursion is not absolutely necessary. It can reduce the lines of code but also can create confusion when following the code or debugging. 
- Some programming languages do not allow it.
Others, like LISP, thrive on it.
- Any task that can bbe accomplished by recursion, can also be done in a non-recursive version, typically this is an iterative version.
- They may use more storage and run slower depending upon the system environment and programming language.



Complex Array Types and Record Types
Read Chapters 10-11 for next week


Assignment #3: Team Units  (due next week)