Ifvar conditions

if<conditional> <gamevar> <constant|gamevar> <then_branch> [else <else_branch>]

ifvar<conditional> <gamevar> <constant> <then_branch> [else <else_branch>]

ifvarvar<conditional> <gamevar> <gamevar> <then_branch> [else <else_branch>]

Ifvar conditions are if conditions that apply to gamevars.

Gamevar conditionals in CON can take only 2 arguments at a time, the first always being the variable being compared against the second operand. The second operand can be a constant, a label or another variable.

If the comparison returns true, the game will execute the code in the <then_branch>. If false, the <else_branch> may be executed if present, otherwise the block is skipped.

The branches may consist of a single command, or if multiple commands need to be executed, a block of code enclosed in curly braces ("{" and "}"). For performance reasons, do not use curly braces for single commands.

To negate a conditional (e.g. you want to compute a nand) place a nullop inside the <then> branch, and put the code to be executed inside the <else> branch.

See also: Else

Chaining if statements

To check for more than a single condition, the if statements will need to be chained.

If done without curly braces, this acts in much the same way as && does in C/C++ syntax. Namely, an else branch that follows the if chain will be executed if any of the preceeding if conditionals returns false.

Example

definequote 100 Hello World
set temp 0

ife temp 1
  ife temp 0
{
    nullop
}
else
{
    // will be executed if either of the above conditionals returns false
    quote 100
}

This may be counterintuitive, as C/C++ and other programming languages only associate the else statement to a single if, usually the one in the same context, which is not the case in CON.

Types of ifvar conditions

Conditional	C/C++	Math	Description
e	==	=	equal to
n	!=	≠	not equal to
g	>	>	greater than
ge	>=	≥	greater or equal
a			above (unsigned greater than)
ae			above or equal (unsigned greater or equal)
l	<	<	less than
le	<=	≤	less or equal
b			below (unsigned less than)
be			below or equal (unsigned less or equal)
and	&		bitwise AND
or	|		bitwise OR
xor	^		bitwise XOR
both	&&		logical AND: both are non-zero
either	||		logical OR: either are non-zero

The above and below operators are useful for validating that a gamevar is a valid index into an array, because by interpreting its value as unsigned when comparing against the array size, you can rule out when the gamevar is negative and when it is larger than or equal to the array size in one comparison operation instead of two.

Commands with an additional "var" suffix take gamevars rather than constants or defined labels for their inputs. As an alternate short form, "varvar" can be dropped from these commands; for example ife serves an an alias for ifvarvare.