Command
	if, else, endif

Purpose
	Directs execution or non-execution of commands or command blocks.

Aliases
	if, else, endif

Syntax
	if <condition>
	<line1>
	[
		else
	  	<line2>
	]
	endif

Options
	None.

Arguments
	<condition>	An expression resulting in a bool constant.
	<line1>	The line to execute if <condition> is true.
	<line2>	The line to execute if <condition> is false.

	Both <line1> and <line2> can have one command or a block of commands enclosed within do...done.

Stream Input	
	Ignored.

Stream Output
	None.

Stream Error
	Any errors are listed here.

Description
	if...else...endif is a programming construct that allows the user to selectively execute, or not execute,
	commands or command blocks.

	<condition> is evaluated at runtime, and not when the command is first entered.
	(Since the if, and any other command, can be inside another programming construct, function, script etc.,
	its run-time value may not be necessarily the same as its parse-time value.)

	Nesting of all programming constructs (while, if...else...endif, do...done, function, etc.) is allowed.
	There is no limit on how many levels of nesting can be done.

	<condition> can contain AND, OR, and NOT bool operators. It is recommended that you use parentheses when
	using these operators. There is no limit on how many, or how many levels of, parentheses can be used.
	
Restrictions
	Stream redirection is not allowed on if, else and endif commands. However, commands within <line1> and <line2>,
	and within do-done command-blocks used in place of <line1> or <line2>, can contain their own stream redirection.

Valid Examples
	var int i
	...	# Value of i is assigned.
	if ($i>0)
	    echo "i is positive"
	endif

	Will print 'i is positive' if i is positive.


Invalid Examples
	var int i
	...
	if ($i)
	echo "i is non-zero"
	endif

	Will produce error. The expression ($i) does not evaluate to a bool value. If the intention is to check
	if i is non-zero, then that condition may be specified in one of the following ways.

	if (makebool(int($i)))
	
	or

	if ($i<>0)

See Also
do
while
makebool