Legacy:UnrealScript Language Reference/Language Functionality

UnrealScript Language Reference

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Tim Sweeney
Epic MegaGames, Inc.
tim@epicgames.com
http://www.epicgames.com

Language Functionality

Built-In Operators And Their Precedence

UnrealScript provides a wide variety of C/C++/Java-style operators for such operations as adding numbers together, comaring values, and incrementing variables. The complete set of operators is defined in Object.u, but here is a recap. Here are the standard operators, in order of precedence.  Note that all of the C style operators have the same precedence as they do in C.

Operator	Types it applies to	Meaning
$	string	String concatenation
*=	byte, int, float, vector, rotation	Multiply and assign
/=	byte, int, float, vector, rotation	Divide and assign
+=	byte, int, float, vector	Add and assign
-=	byte, int, float, vector	Subtract and assign
||	bool	Logical or
&&	bool	Logical and
&	int	Bitwise and
|	int	Bitwise or
^	int	Bitwise exlusive or
!=	all	Compare for inequality
==	all	Compare for equality
<	byte, int, float, string	Less than
>	byte, int, float, string	Greater than
<=	byte, int, float, string	Less than or equal to
>=	byte, int, float, string	Greater than or equal to
~=	float, string	Approximate equality (within 0.0001), case-insensitive equality
<<	int, vector	Left shift (int), Forward vector transformation (vector)
>>	int, vector	Right shift (int), Reverse vector transformation (vector)
+	byte, int, float, vector	Add
-	byte, int, float, vector	Subtract
%	float	Modulo (remainder after division)
*	byte, int, float, vector, rotation	Multiply
/	byte, int, float, vector, rotation	Divide
dot	vector	Vector dot product
cross	vector	Vector cross product
**	float	Exponentiation

The above table lists the operators in order of precedence (with operators of the same precedence grouped together). When you type in a complex expression like "1*2+3*4", UnrealScript automatically groups the operators by precedence. Since multiplication has a higher precedence than addition, the expression is evaluated as "(1*2)+(3*4)".

The "&&" (logical and) and "||" (logical or) operators are short-circuited: if the result of the expression can be determined solely from the first expression (for example, if the first argument of && is false), the second expression is not evaluated.

In addition, UnrealScript supports the following unary operators:

Operator	Types it applies to	Meaning
!	bool	Logical not
-	int, float	negation
~	int	bitwise negation
++, --	int, float	Increment or Decrement (either before or after a variable)

more on this topic in the Wiki: Operators

General-Purpose Functions

Integer functions:

int Rand( int Max ) 

Returns a random number from 0 to Max-1.

int Min( int A, int B ) 

Returns the minimum of the two numbers.

int Max( int A, int B ) 

Returns the maximum of the two numbers.

int Clamp( int V, int A, int B ) 

Returns the first number clamped to the interval from A to B.

Floating point functions:

float Abs( float A )

Returns the absolute value of the number.

float Sin( float A )

Returns the sine of the number expressed in radius.

float Cos( float A )

Returns the cosine of the number expressed in radians.

float Tan( float A )

Returns the tangent of the number expressed in radians.

float Atan( float A )

Returns the inverse tangent of the number expressed in radians.

float Exp( float A )

Returns the constant "e" raised to the power of A.

float Loge( float A )

Returns the log (to the base "e") of A.

float Sqrt( float A )

Returns the square root of A.

float Square( float A )

Returns the square of A = A*A.

float FRand()

Returns a random number from 0.0 to 1.0.

float FMin( float A, float B )

Returns the minimum of two numbers.

float FMax( float A, float B )

Returns the maximum of two numbers.

float FClamp( float V, float A, float B )

Returns the first number clamped to the interval from A to B.

float Lerp( float Alpha, float A, float B )

Returns the linear interpolation between A and B.

float Smerp( float Alpha, float A, float B )

Returns an Alpha-smooth nonlinear interpolation between A and B.

Unreal’s string functions have a distinct Basic look and feel:

int Len( coerce string[255] S )

Returns the length of a string.

int InStr( coerce string[255] S, coerce string[255] t)

Returns the offset into the first string of the second string if it exists, or -1 if not.

string[255] Mid ( coerce string[255] S, int i, optional int j )

Returns the middle part of the string S, starting and character i and including j characters (or all of them if j is not specified).

string[255] Left ( coerce string[255] S, int i )

Returns the i leftmost characters of s.

string[255] Right ( coerce string[255] S, int i )

Returns the i rightmost characters of s.

string[255] Caps ( coerce string[255] S )

Returns S converted to uppercase.

Vector functions:

float Size( vector A )

Returns the euclidean size of the vector (the square root of the sum of the components squared).

vector Normal( vector A )

Returns a vector of size 1.0, facing in the direction of the specified vector.

Invert ( out vector X, out vector Y, out vector Z )

Inverts a coordinate system specified by three axis vectors.

vector VRand ( )

Returns a uniformly distributed random vector.

float Dist ( vector A, vector B )

Returns the euclidean distance between two points.

vector MirrorVectorByNormal( vector Vect, vector Normal )

Mirrors a vector about a specified normal vector.

more on this topic in the Wiki: Global Function

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