UnrealScript

UnrealScript

Paradigm	Object-oriented, generic
Developer	Tim Sweeney
First appeared	1998
Typing discipline	Static, strong, safe
OS	Cross-platform (multi-platform)
Filename extensions	.uc .uci .upkg
Website	udn.epicgames.com
Influenced by
C++, Java

UnrealScript (often abbreviated to UScript) is the scripting language of the Unreal Engine and is used for authoring game code and gameplay events. The language was designed for simple, high-level game programming. The UnrealScript interpreter was programmed by Tim Sweeney, who also created an earlier game scripting language, ZZT-oop.

Similar to Java, UnrealScript is object-oriented without multiple inheritance (classes all inherit from a common Object class), and classes are defined in individual files named for the class they define. Unlike Java, UnrealScript is case-insensitive, and does not have object wrappers for primitive types. Interfaces are only supported in Unreal Engine generation 3 and a few Unreal Engine 2 games. UnrealScript supports operator overloading, but not method overloading, except for optional parameters.

By making the process of modifying the game easier, UnrealScript helped enable the growth of a large modding community around Unreal. This greatly added to the overall longevity of Unreal and provided an incentive for new development.

Syntax

Code comments

File:Unreal X-Editor v3.0.png

Unreal X-Editor showing syntax highlight using one of the in-built color scheme.

UnrealScript uses two commenting styles, a single-line comment (beginning with // until the end of the line) and a multi-line comment (delimited by /* and */).

// Single-line comment
class Foo extends Object;

/* Multi-line
   comment */
var Object Foo;

Functions

UnrealScript uses functions similar to C/C++. Functions are declared by the keyword: function, the return type: int, the name: example_function, and finally the function parameters enclosed in parenthesis: (int example_number).

The body is enclosed in brackets: { example_number = 5; }.

Before the final bracket, a return function can be called, returning the a value to the original caller.

function int example_function (int example_number)
{
   example_number = 5;
   return example_number;
}

This function takes the integer example_number, changes its value to 5, then returns its value to the caller.

"Hello, world" example

The following is a hello world example using the syntax of UnrealScript.

class HelloWorld extends GameInfo;

event InitGame( string Options, out string Error )
{
    `log( "Hello, world!" );
}

The following text will be printed to the output console when HelloWorld is initializing:

Hello, world!

See also

IDEs

• WOTgreal - Integrated development environment for UnrealScript
• nFringe - A Microsoft Visual Studio plug-in for UnrealScript
• Unreal Writer - A basic UnrealScript editor for Mac OS X
• Unreal Script IDE A UnrealScript IDE using Microsoft Visual Studio shell
• Unreal X-Editor - A Free UnrealScript Editor
• Unreal Script Wizard - A Free Unreal Script Wizard
• UnrealScript IDE for Sublime Text 2 - A Plugin for Sublime Text 2
• Unreal Sed - Free IDE for Unreal, Unreal 2, UT, UT2003, UT2004, UT3 and UDK.

Utilities

• UnCodeX - An application to browse source code of UnrealScript
• UTPT - An application to decompile, and export sounds, textures, and meshes from Unreal Engine 1, and 2's packages
• UE Viewer - An application to export sounds, textures, and meshes from Unreal Engine 1, 2, and 3's packages
• UE Explorer - An application to decompile UnrealScript from Unreal Engine 1, 2, and 3's packages

Other

• Unreal Developer Network - The official wiki
• UnrealWiki - The unofficial wiki

External links

• UnrealScript Language Reference for UE2
• UnrealScript Language Reference for UE3
• UnrealScript Language Reference circa 1998 (Original Unreal)
• UnrealWiki: UnrealScript