Difference between revisions of "Typecast"

Revision as of 07:10, 17 April 2009

LSL Portal

To convert the type of a value a typecast is required. There are two types of typecasting, explicit and implicit. Explicit typecasts must be provided by the programmer, but implicit typecasts are put in place by the compiler. LSL implicitly typecasts strings to keys and integers to floats where the latter type is required but the former is provided.

Supported Typecasts
		To
		integer	float	string	key	list	vector	rotation
From	integer	x	x	x		x
	float	x	x	x		x
	string	x	x	x	x	x	x	x
	key			x	x	x
	list			x		x
	vector			x		x	x
	rotation			x		x		x

Syntax: (type)value

Converts value to type.

• expression	type	–	variable type
• expression	value	–	expression or constant

If value is a complex expression, it may be beneficial to wrap it in parentheses. (type)(value)

Examples

<lsl> string a = "1.5"; float b = (float)a; integer c = (integer)a;

integer i; i = (integer) 1.23; // 1 i = (integer) -1.23; // -1 i = (integer) "0123"; // 123 i = (integer) "0x12A"; // 298

float f; f = (float) "6.2e1"; // 62.0 // "6.2e1", "6.2e+1", "6.2E1", "6.2E+1" are all equivalent.

string s; s = (string) [1, 2.3, "a"]; // "12.300000a" s = (string) <1.0, 2.3, 4.56>; // "<1.00000, 2.30000, 4.56000>"

list l; l = (list) ""; // [""] l = (list) <1.0, 2.3, 4.56>; // ["<1.00000, 2.30000, 4.56000>"]

vector v; v = (vector) "<1.0, 2.3, 4.56>"; // <1.0, 2.3, 4.56> v = (vector) "<1.0, 2.3>"; // ZERO_VECTOR (Due to insufficient value)

rotation r; r = (rotation) "<1.0, 2.3, 4.56, 1.0>"; // <1.0, 2.3, 4.56, 1.0> r = (rotation) "<1.0, 2.3, 4.56>"; // ZERO_ROTATION (Due to insufficient value) </lsl>

Example n°2

<lsl> integer BOOT_TIME; float BOOT_TIME_2; string BOOT_T ; string BOOT_CHAN;

default

{

   state_entry()
   {
      BOOT_TIME = llGetUnixTime(); 
      BOOT_T = (string)BOOT_TIME;
      BOOT_TIME_2 = llGetTimeOfDay();
      BOOT_CHAN = (string)BOOT_TIME_2;
        llSetObjectDesc( BOOT_T);
        llSetText(BOOT_CHAN,<1.0,0.0,0.0>,1.0);
   }

} </lsl>

Caveats

The compiler allows explicit typecasting where it is not needed and does not optimize it out. Unnecessary typecasts will bloat code and slow it down.

Notes

For getting at the elements of a list use the llList2* functions.