Relational Expressions in C
---------------------------

Terms
-----

flow of control		Refers to the order in which a program's statements
			are executed.

sequential flow		Step-by-step progression of statements in a program.
			Normal flow of program execution unless otherwise
			directed.

selection statements	Provide the ability to select which statement will be
			executed next (take the flow out of sequential flow).

repetition statements	Provide the ability to go back and repeat a set of 
			statements (looping control flow of statements).

relational expressions	Expressions used to compare operands.


Simple Relational Expressions
-----------------------------

	age > 40
	length <= 20
	hours < 8
	flag == done


Valid Relational Expressions
----------------------------

	relational	meaning				example
	operator
	----------	-----------------------------	--------------------
	   <		less than			i < 32
	   >		greater than			i > 89
	   <=		less than or equal to		i <= 13
	   >=		greater than or equal to	i >= -44
	   ==		equal to			i == 8
	   !=		not equal to			i != 0

	----------
	logical
	operator
	----------
	   ||		logical OR			a == 6 || a == 7
	   &&		logical AND			b == 5 && c < 10


Invalid Relational Expressions
------------------------------

	length =< 10		should be <=
	flag = = done		should be ==
	3 >> 2			should be >


Format of an Expression
-----------------------

The simple format is of the form:

	operand1 relational-operator operand2

An example, again, is:

	a < 2

The more complex form is:

	(operand1 rel-operator operand2) logical-operator 
	(operand3 rel-operator operand4) logical-operator etc...

Example are:

	(a < 3) && (b > c) && (rad == 2)

	(apple == banana) || (i <= 10)

	((i < 10) && (i > 5)) || (j < 10)


Evaluation of Relational Expressions
------------------------------------

Given the following assignments:

	char key = 'm';
	int i = 5;
	int j = 7;
	int k = 12;
	double x = 22.5;

Example 1
---------

	i + 2 == k - 1
	5 + 2 == 12 - 1
	7 == 11

	False, since 7 is not equal to 11.  False is represented by 0 (true
		us represented by anything but 0).

Example 2
---------

	key + 3 > 'p'
	'm' + 3 > 'p'
	'p' > 'p'

	False, since 'p' is equal to 'p'.


Exercises 4.1 -- Problem #4
---------------------------

	a = 5
	b = 2
	c = 4
	d = 5

	a)	a==5
		5==5
		True

	b)	b*d == c*c
		2*5 == 4*4
		10  == 16
		False

	c)	d%b*c > 5 || c%b*d < 7
		5%2*4 > 5 || 4%2*5 < 7
		5%8 > 5   || 4%10  < 7
		5   > 5   || 4     < 7
		False	  || True
		True

	This is True since either one is acceptable in the logical OR.