Dynamic arrays - Revision history

Krillin6: /* Accessing and modifying the array length */

2012-05-15T23:11:25Z

‎Accessing and modifying the array length

Wormbo: /* Additional array operations in Unreal Engine 3 */ improved description for sort()

2010-08-20T11:30:07Z

‎Additional array operations in Unreal Engine 3: improved description for sort()

Wormbo: /* Additional array operations in Unreal Engine 3 */ added Sort operation

2010-08-09T07:01:29Z

‎Additional array operations in Unreal Engine 3: added Sort operation

00zX: /* Usage in code */ - fixed a typo

2010-04-20T20:46:16Z

‎Usage in code: - fixed a typo

Wormbo: /* See also */ changed external to interwiki links

2009-12-13T12:06:08Z

‎See also: changed external to interwiki links

86.42.91.171: Shambler: Example code would end up skipping an element

2009-07-05T16:10:15Z

Shambler: Example code would end up skipping an element

Wormbo: /* Declaration syntax */ mentioned compiler bug with arrays of class limiter/delegate types

2008-12-27T10:07:05Z

‎Declaration syntax: mentioned compiler bug with arrays of class limiter/delegate types

Wormbo: added usage in defaultproperties and mentioned array iteration via ForEach

2008-12-27T10:02:26Z

added usage in defaultproperties and mentioned array iteration via ForEach

Wormbo: added usage in code and unrealed and provided UDN links

2008-12-24T14:24:18Z

added usage in code and unrealed and provided UDN links

Wormbo: first pass

2008-12-19T19:51:41Z

first pass

New page

'''Dynamic arrays''' are a special [[Types#Composite types|composite type]] in [[UnrealScript]] that contains a variable number of elements in a well-defined order. These elements all have the same type, called the "inner type" of the array.

UnrealScript's dynamic arrays are a true [[wp:dynamic array|dynamic array]] implementation, i.e. unlike [[wp:Java (programming language)|Java]]'s dynamically-allocated fixed-size arrays they can be resized at runtime.
The type declaration syntax was available (almost) from the start, but [[Unreal Engine 1]] never provided any way to actually access or modify them at the UnrealScript level. In other words, dynamic arrays are fully usable in UnrealScript only in [[Unreal Engine 2]] and later.

Unlike any other data type in UnrealScript, dynamic arrays have absolutely no support for [[replication]]. Attempting to replicate a dynamic array variable will have no effect on the remote instance of that variable. Attempting to use a dynamic array as parameter of a [[replicated function]] will result in the parameter being empty when the function is executed on the remote side.

==Declaration syntax==
Dynamic arrays are declared as part of the type:
'''array<''' type '''>'''

The inner type of a dynamic array can be a [[class limiter]] or the name of any other non-array type, including [[delegate]] types. Note that [[Unreal Engine 2]] does not support dynamic arrays of type [[bool]] and the compiler will complain accordingly. Dynamic arrays of bool values are possible in [[Unreal Engine 3]], though.

A dynamic array type can be used in all places that allow a type definition. The following example code defines a class-global dynamic array of bytes and a function that uses dynamic arrays as return type and as the type of a parameter and a local variable:
<uscript>
var array<byte> ByteArray;

function array<int> RoundAll(array<float> Values)
{
local array<int> Result;

//...

return Result;
}
</uscript>
The only exception are type declarations of [[variables]], [[struct]] members and [[function]] parameters that are declared as [[static arrays]]. In this case, the dynamic array declaration is ignored.

==Usage in code==
{{sectstub}}

==Usage in defaultproperties block==
{{sectstub}}

==Usage in UnrealEd==
{{sectstub}}
[[Image:UnrealEd3-Properties-DynArrayButtons.png|left|Buttons for modifying dynamic array properties in [[UnrealEd 3]].]]
[[Image:UT3-UnrealEd-Properties-DynArrayButtons.png|right|Buttons for modifying dynamic array properties in [[UT3 UnrealEd]].]]

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@@ Line 57: / Line 57: @@
 The length of an array can be retrieved with the following syntax:
   ''arrayreference'''''.Length'''
 If used on the left side of the simple assignment operator, this syntax can also be used to add or remove elements to/from the array. Like all operations that add elements to the array, this will initialize the new elements with the null value of the array's inner type. '''Important:''' The ''Length'' attribute must not be used on the left side of combined assignment operators or passed to a function parameter declared with the ''out'' modifier!
 ===Inserting and removing elements===

@@ Line 104: / Line 104: @@
 Starting with newer versions of the Unreal Engine 3 there is also a simply way to sort an array:
-  ''arrayreference'''''.Sort('''''sortdelegate''''')'''
+  ''arrayreference'''''.Sort('''''comparefunction''''')'''
-The ''sortdelegate'' is the name of a function ''(or delegate? {{confirm}})'' that takes two parameters of the array's element type and returns a value of type [[int]]. Negative return values indicate that the first parameter should come after the second, i.e. the values are not in order. Zero or positive return values mean the two elements should stay in the order they are now.
+The ''comparefunction'' is the name of a function that takes two parameters of the array's element type and returns a value of type [[int]]. Negative return values indicate that the first parameter should come after the second, i.e. the values are not in order. Positive return values mean the first element should come before the second, i.e. they are in order. Zero means the elements are equal and thus in order. The magnitude of the positive or negative return value don't matter, only its sign.
 ==Usage in defaultproperties block==

@@ Line 96: / Line 96: @@
 </uscript>
-Finally, Unreal Engine 3 offers two methods to search for values in an array. The simple version just looks for a value:
+Unreal Engine 3 also offers two methods to search for values in an array. The simple version just looks for a value:
   ''arrayreference'''''.Find('''''value''''')'''
 This returns the index of the first element containing the specified value. If the array doesn't contain this value, <code>INDEX_NONE</code> is returned, i.e. the value -1.
@@ Line 102: / Line 102: @@
   ''arrayreference'''''.Find('''''membername''''',''' ''value''''')'''
 The member name must be a [[name]] literal specifying the name of a struct member variable.
 ==Usage in defaultproperties block==

@@ Line 43: / Line 43: @@
 An access method only available in [[Unreal Engine 3]] is iteration via the [[foreach loop]]:
-  '''foreach''' ''arrayreference'''''('''''valuevariable'' [''',''' ''indexvariable'']''') {'''
+  '''foreach''' ''arrayreference'''''('''''valuevariable'' ''',''' [''indexvariable'']''') {'''
     ...
   '''}'''

@@ Line 149: / Line 149: @@
 {{clear}}
 ==See also==
-* [http://udn.epicgames.com/Two/UnrealScriptReference.html#DynArray UnrealScript Language Reference/Dynamic Arrays] (Unreal Engine 2)
+* [[udn2:UnrealScriptReference#DynArray|UnrealScript Language Reference/Dynamic Arrays]] (Unreal Engine 2)
-* [http://udn.epicgames.com/Three/UnrealScriptReference.html#DynArray UnrealScript Language Reference/Dynamic Arrays] (Unreal Engine 3)
+* [[udn3:UnrealScriptReference#DynArray|UnrealScript Language Reference/Dynamic Arrays]] (Unreal Engine 3)
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@@ Line 91: / Line 91: @@
 for (i = 0; i < arrayreference.length; ++i) {
    if (arrayreference[i] == value) {
-     arrayreference.Remove(i, 1);
+     arrayreference.Remove(i--, 1);
+   }
+}

← Older revision		Revision as of 10:07, 27 December 2008
Line 11:		Line 11:

	The inner type of a dynamic array can be a [[class limiter]] or the name of any other non-array type, including [[delegate]] types. Note that [[Unreal Engine 2]] does not support dynamic arrays of type [[bool]] and the compiler will complain accordingly. Dynamic arrays of bool values are possible in [[Unreal Engine 3]], though.		The inner type of a dynamic array can be a [[class limiter]] or the name of any other non-array type, including [[delegate]] types. Note that [[Unreal Engine 2]] does not support dynamic arrays of type [[bool]] and the compiler will complain accordingly. Dynamic arrays of bool values are possible in [[Unreal Engine 3]], though.
		+
		+	Be careful when declaring a dynamic array of a [[class limiter]] or [[delegate]] type. The compiler recognized two consecutive <code>></code> characters as the [[operator]] <code>>></code> and will fail with a syntax error. Insert whitespace to get around this limitation:
		+	'''array< class<''' classname '''> >'''

	A dynamic array type can be used in all places that allow a type definition. The following example code defines a class-global dynamic array of bytes and a function that uses dynamic arrays as return type and as the type of a parameter and a local variable:		A dynamic array type can be used in all places that allow a type definition. The following example code defines a class-global dynamic array of bytes and a function that uses dynamic arrays as return type and as the type of a parameter and a local variable:

@@ Line 38: / Line 38: @@
 The same syntax can be used for assigning values to individual array elements. In this case the index must be non-negative, but may exceed the array length. If the index is equal to or greater than the current length of the array, the array grows so its last element has the specified index, i.e. its length is now <code>index + 1</code>. If you can estimate the final number of elements an array will have, you can resize it manually before assigning the values.
 ===Accessing and modifying the array length===
@@ Line 89: / Line 101: @@
 ==Usage in defaultproperties block==
-{{sectstub}}
+The default data for a dynamic array can either be specified per element, similar to [[static arrays]], or for the entire array at once.
 ==Usage in UnrealEd==

@@ Line 28: / Line 28: @@
 ==Usage in code==
-{{sectstub}}
+Dynamic arrays provide various ways for reading and manipulating the content and length of the array. All of these must be done through variables or struct members, dynamic arrays returned from functions must be assigned to a variable first.
 ==Usage in defaultproperties block==
@@ Line 34: / Line 92: @@
 ==Usage in UnrealEd==
-{{sectstub}}
+[[Image:UnrealEd3-Properties-DynArrayButtons.png|thumb|363px|An actor's [[UE2:Actor properties (UT2004)#Skins|Skins]] material array property in [[UnrealEd 3]].]]
-[[Image:UnrealEd3-Properties-DynArrayButtons.png|left|Buttons for modifying dynamic array properties in [[UnrealEd 3]].]]
+Using and modifying dynamic array properties in [[UnrealEd]] property windows is pretty straight-forward with the buttons provided by the property window.
-[[Image:UT3-UnrealEd-Properties-DynArrayButtons.png|right|Buttons for modifying dynamic array properties in [[UT3 UnrealEd]].]]
+[[Image:UT3-UnrealEd-Properties-DynArrayButtons.png|thumb|375px|The [[UE3:WorldInfo (UT3)#GameTypesSupportedOnThisMap|GameTypesSupportedOnThisMap]] class array property in [[UT3 Editor]]'s [[world properties]].]]
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