Difference between revisions of "Do while"
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m (Changed example so it now compiles.) |
Lady Sumoku (talk | contribs) m (Replaced old <LSL> block with <source lang="lsl2">) |
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|spec | |spec | ||
|caveats | |caveats | ||
|examples=< | |examples=<source lang="lsl2">//Counts from 1 to 5 | ||
default | default | ||
{ | { | ||
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while (olf < 5); // On the first pass/loop olf = 1 | while (olf < 5); // On the first pass/loop olf = 1 | ||
} | } | ||
}</ | }</source><source lang="lsl2">//Counts from 0 to 4 | ||
default | default | ||
{ | { | ||
| Line 37: | Line 37: | ||
while (++olf < 5); // Increments then does the while-test | while (++olf < 5); // Increments then does the while-test | ||
} | } | ||
}</ | }</source><source lang="lsl2">//Counts from 0 to 4 and comments as it loops (block statement demo) | ||
default | default | ||
{ | { | ||
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while (++olf < 5); | while (++olf < 5); | ||
} | } | ||
}</ | }</source><source lang="lsl2"> | ||
//Practical example of where a do/while loop is more immediately useful than a while loop: | //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 | //Note that a sensor event always contains input data, so the 'do' always has something to process | ||
| Line 66: | Line 66: | ||
llDialog(llGetOwner(), "Choose an avatar.", gNameList, gDlgChan); //channel is pre-defined when llSensor is triggered | llDialog(llGetOwner(), "Choose an avatar.", gNameList, gDlgChan); //channel is pre-defined when llSensor is triggered | ||
} | } | ||
</ | </source> | ||
|helpers | |helpers | ||
|also_header | |also_header | ||
Latest revision as of 01:12, 22 January 2015
| LSL Portal | Functions | Events | Types | Operators | Constants | Flow Control | Script Library | Categorized Library | Tutorials |
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
//Counts from 1 to 5
default
{
state_entry()
{
integer olf; // Without applied value an integer will be defaulted to zero.
do
llSay(0, (string) (++olf)); // Increment before the while condition
while (olf < 5); // On the first pass/loop olf = 1
}
}
//Counts from 0 to 4
default
{
state_entry()
{
integer olf;
do
llSay(0, (string)olf); // olf is still equal to zero at first iteration
while (++olf < 5); // Increments then does the while-test
}
}
//Counts from 0 to 4 and comments as it loops (block statement demo)
default
{
state_entry()
{
integer olf;
do
{ // Curly brackets are required since there is more than one statement within the do-loop
llSay(0, (string)olf);
llSay(0, "looping");
}
while (++olf < 5);
}
}
//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 (num > 12)
num = 12;
do
{
// --num decrements num before using it to pick up a detected avatar's name. Thus we retrieve #11 through #0
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 (num > 0);
llDialog(llGetOwner(), "Choose an avatar.", gNameList, gDlgChan); //channel is pre-defined when llSensor is triggered
}
Deep Notes
Footnotes
- ^ The OpenSim LSL compiler will not do this implicitly. You will need to use an explicit check.