Difference between revisions of "Do while"

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(Removed div styling to reduce width of entry and to maintain continuity and added a few notes to old examples.)
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|spec
 
|spec
 
|caveats
 
|caveats
|examples=<div style="display:inline-block; vertical-align:top;"><lsl>//Counts from 1 to 5
+
|examples=<lsl>//Counts from 1 to 5
 
default
 
default
 
{
 
{
 
     state_entry()
 
     state_entry()
 
     {
 
     {
         integer olf;
+
         integer olf;// Without applied value an integer will be defaulted to zero.
 
         do
 
         do
             llSay(0, (string) (++olf));
+
             llSay(0, (string) (++olf));// Increment before the while condition.
         while(olf<5);
+
         while(olf<5);                 // On the first pass/loop olf = 1
 
     }
 
     }
}</lsl></div>
+
}</lsl><lsl>//Counts from 0 to 4
<div style="display:inline-block; vertical-align:top;"><lsl>//Counts from 0 to 4
+
 
default
 
default
 
{
 
{
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         integer olf;
 
         integer olf;
 
         do
 
         do
             llSay(0, (string)olf);
+
             llSay(0, (string)olf);// olf is still equal to zero.
         while((++olf)<5);
+
         while((++olf)<5);// Increment after/during the test.
 
     }
 
     }
}</lsl></div>
+
}</lsl><lsl>//Counts from 0 to 4 and coments as it loops (block statement demo)
<div style="display:inline-block; vertical-align:top;"><lsl>//Counts from 0 to 4 and coments as it loops (block statement demo)
+
 
default
 
default
 
{
 
{
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         do
 
         do
 
         {
 
         {
             llSay(0, (string)olf);
+
             llSay(0, (string)olf);// Curly brackets are required since there is more than one looped command.
 
             llSay(0, "looping");
 
             llSay(0, "looping");
 
         }
 
         }
 
         while((++olf)<5);
 
         while((++olf)<5);
 
     }
 
     }
}</lsl></div>
+
}</lsl><lsl>
<div style="display:inline-block; vertical-align:top;">
+
<lsl>
+
 
//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
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         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
 
     }
 
     }
</lsl></div>
+
</lsl>
 
|helpers
 
|helpers
 
|also_header
 
|also_header

Revision as of 03:02, 3 October 2009

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.

Specification

Conditional Types
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.

Examples

<lsl>//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
   }

}</lsl><lsl>//Counts from 0 to 4 default {

   state_entry()
   {
       integer olf;
       do
           llSay(0, (string)olf);// olf is still equal to zero.
       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
       {
           llSay(0, (string)olf);// Curly brackets are required since there is more than one looped command.
           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(num>12)
           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(num>0);
       llDialog(llGetOwner(),"Choose an avatar.",gNameList,gDlgChan);//channel is pre-defined when llSensor is triggered
   }

</lsl>

Deep Notes

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Footnotes

  1. ^ The OpenSim LSL compiler will not do this implicitly. You will need to use an explicit check.