Difference between revisions of "If"

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imported>Gblues
(Moving the comparison operator list from the "commands" topic.)
imported>Gblues
(Added overview, else/elseif/endif information)
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The <tt>if</tt> statement allows you to execute (or not execute) a block of script commands based on one or more comparisons that you specify. Oblivion's <tt>if</tt> command is very powerful and comparable to "real" programming languages.
The <tt>if</tt> statement allows you to execute (or not execute) a block of script commands based on one or more comparisons that you specify. Oblivion's <tt>if</tt> command is very powerful and comparable to "real" programming languages.
== Overview ==
An if statement uses the following syntax:
<pre>
if expressionA [comparison] expressionB
; test "expressionA [comparison] expressionB" passed
elseif expressionB [comparison] expressionC
; test "expressionB [comparison] expressionC" passed
else
; none of the above tests passed
endif
</pre>
The <tt>else</tt> and <tt>elseif</tt> statements are optional.


== Comparison Operators ==
== Comparison Operators ==
Line 64: Line 80:
  IF a * ( 5 + c ) - 14 == b
  IF a * ( 5 + c ) - 14 == b
  IF 2*(a*(5+c)-14)==b - -b
  IF 2*(a*(5+c)-14)==b - -b


[[Category:Commands]]
[[Category:Commands]]

Revision as of 02:06, 15 April 2006

The if statement allows you to execute (or not execute) a block of script commands based on one or more comparisons that you specify. Oblivion's if command is very powerful and comparable to "real" programming languages.

Overview

An if statement uses the following syntax:

if expressionA [comparison] expressionB
; test "expressionA [comparison] expressionB" passed
elseif expressionB [comparison] expressionC
; test "expressionB [comparison] expressionC" passed
else
; none of the above tests passed
endif

The else and elseif statements are optional.

Comparison Operators

An if statement may contain one or more comparison operators. Below is a table of valid comparison operators:

Operator Description
== Exactly equal to
!= Not equal to
> Greater than
>= Greater than or equal to
< Less than
<= Less than or equal to

It is important to note that there are no bitwise comparisons available in Oblivion's scripting language.

Combining Comparisons

Comparisons can be linked together using the following logical operators:

Operator Description Example
&& Logical AND if x == 1 && y == 1 ; considered true only if both x and y equal 1.
|| Logical OR if x == 1 || y == 1 ; considered true unless both x and y equal 0.

Comparisons and Expressions

The comparison operators can be used with any expression that can be evaluated into a number. Assuming "a = 17", "b = 20" and "c = a - b", all of the following expressions work as expected. Parentheses are only needed when they're necessary for mathematical or logical reasons.

IF c == -3 && b == 20
IF c == -3 && b == 20 && a == 17
IF c - 1 == -4 && b == 20 && a == 17
IF a - 20 == 17 - b
IF a - 20 == 17 - b && c + 3 == 0
IF a + 3 == b
IF a - b == c
IF a *4 - b * 4 == c * 4
IF a * ( 5 + c ) - 14 == b
IF 2*(a*(5+c)-14)==b - -b