The switch Control Statement
----------------------------

The "if-else" chain is used in programming applications where one set of 
instructions must be selected from many possible alternatives.  The "switch"
statement provides an alternative and has a shorter format.  The format is:

	switch (expression)
	{
	  case value_1:
	    statement1_1;
	    statement1_2;
		:
	    statement1_n;
	    break;

	  case value_2:
	    statement2_1;
	    statement2_2;
		:
	    statement2_n;
	    break;

		:
		:

	  default:
	    statementm_1;
	    statementm_2;
		:
	    statementm_n;
	}

Note: Look carefully where the colons are and semicolons (see book page 143
      and page 144.

An example of it's usage is:

	switch (a)
	{
	  case 1:
	    printf("value is 1\n");
	    break;

	  case 2:
	    printf("value is 2\n");
	    break;

	  default:
	    printf("value is something else\n");
	}

The switch statement above takes the variable called "a" and checks it's
contents.  If it has the value of 1 it goes to the case 1's area.  If it
has a value of 2 it goes to the case 2's area.  If it has any other value,
it goes to the default area.

Let's try a problem.

	Problem: Let Monday thru Friday be represented by numbers 1-5.
		 Set up a condition such that on Monday and Wednesday
		 it will say "go to class".  On the other days, "party the
		 night before and sleep in".  Input the weekday via args.

	#include <stdio.h>
	#include <stdlib.h>

	main(int argc, char **argv)
	{
	  int day = atoi(argv[1]);

	  switch (day)
	  {
	    case 1:
	    case 3:
	      printf("go to class\n");
	      break;

	    case 2:
	    case 4:
	    case 5:
	      printf("party the night before and sleep in\n");
	      break;

	    default: /* do nothing */
	      break;
	  }
	}

The output is:

	delacroix:/u/greg/VIZA652/c_book2% pro4 1
	go to class
	delacroix:/u/greg/VIZA652/c_book2% pro4 2
	party the night before and sleep in
	delacroix:/u/greg/VIZA652/c_book2% pro4 3
	go to class
	delacroix:/u/greg/VIZA652/c_book2% pro4 4
	party the night before and sleep in
	delacroix:/u/greg/VIZA652/c_book2% pro4 5
	party the night before and sleep in
	delacroix:/u/greg/VIZA652/c_book2% pro4 6


Exercises 4.4 -- Problem #4
---------------------------

	Determine why the if-else chain in program 4-5 (in C book) cannot
	be replaced with a switch statement?

	Answer: The if-else statement in there contains a range of values.
		You would need to test for each value like >= 50000.00 .

		case 50000.00
		case 50000.01
		case 50000.02

			:

		Can you imagine how long this would be?? Thus you cannot do
		it since the numbers of floating point and there is a large
		range of numbers that would exhaust your computer's memory and
		your time (in fact you would never finish it).