Do while
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do loop while (condition);
• | loop | – | Executes once, then executes condition. | |
• | condition | – | If condition executes true, it then loops back and executes loop again. |
Any of the statements can be null statements. A do...while loop is slightly faster than a while or for loop, and requires fewer bytes of memory than a while or for loop. (However, the speed increase and byte difference does not apply to scripts compiled in Mono)
Specification
Type | Condition |
---|---|
integer | True if it is not zero. |
float | True if it is not zero.[1] |
string | True if its length is not zero. |
key | True only if it is a valid key and not NULL_KEY. |
vector | True if the vector is not ZERO_VECTOR. |
rotation | True if the rotation is not ZERO_ROTATION. |
list | True if the length is not zero. Note that correct behavior is only seen with Mono-compiled scripts; LSO-compiled scripts incorrectly resolve to false if the list is non-empty: BUG-230728 |
Examples
<lsl> //Counts from 1 to 5
default {
state_entry() { integer olf;// Without applied value an integer will be defaulted to zero.
do
// {
// Increment before the while condition. llSay(0, (string) (++olf));
// }
while(olf < 5);// On the first pass/loop olf = 1 }
} </lsl> <lsl> //Counts from 0 to 4
default {
state_entry() { integer olf;
do
// {
// olf is still equal to zero.
llSay(0, (string)olf);
// }
while(++olf < 5);// Increment after/during the test. }
} </lsl> <lsl> //Counts from 0 to 4 and coments as it loops (block statement demo)
default {
state_entry() { integer olf;
do { // Curly brackets are required since there is more than one looped command.
llSay(0, (string)olf); llSay(0, "looping"); } while (++olf < 5); }
} </lsl> <lsl> //Practical example of where a do/while loop is more immediately useful than a while loop: //Note that a sensor event always contains input data, so the 'do' always has something to process
sensor(integer num) { if (12 < num) num = 12;
do { gNameList += [llGetSubString(llDetectedName(--num),0,23)]; // sometimes avatar names are too long for dialog display gKeyList += [llDetectedKey(num)]; // we will dialog select avatar by name, but still need their key // even if their name has not been truncated above } while (0 < num);
llDialog(llGetOwner(),"Choose an avatar.", gNameList, gDlgChan);// channel is pre-defined when llSensor is triggered }
</lsl>
See Also
Deep Notes
Footnotes
- ^ The OpenSim LSL compiler will not do this implicitly. You will need to use an explicit check.