For

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for( initializer; condition; increment ) loop

•	initializer	–	Executed once just before checking condition.
•	condition	–	If this executes as true then loop is executed.
•	increment	–	Executed after loop, then condition is checked again.
•	loop	–	Can be either a single statement, a block statement, or a null statement.

Only the condition is required. The initializer, increment, and loop body are optional and can be left empty.

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. 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

The following is the most common way a for-loop is written, with each part properly specified.

The loop will run or "iterate" 10 times, from 0 to 9. It will execute two statements each iteration.

integer a = 0;
integer b = 10;
for (a = 0; a < b; ++a)
{
    llOwnerSay( (string)a ); // first statement
    llOwnerSay( (string)b ); // second statement
}

The following is less common, where the curly braces are left out.

This can be used when only one statement needs to be executed during the loop.

integer a = 0;
integer b = 10;
for (a = 0; a < b; ++a)
    llOwnerSay( (string)a ); // single statement

Although the following is technically possible, it's not recommended because it's hard to read and maintain.

The initialization is left out because the variable a already has the value zero.

The loop body is left out because the increment statement includes a function call which does everything that's needed.

integer a = 0;
integer b = 10;
for ( ; a < b; llOwnerSay((string)(++a)) )
    ; // empty statement (could be at the end of the previous line)

Notes

A for-loop can also be written as a While-loop.

initializer;
while(condition)
{
    loop;
    increment;
}

Deep Notes

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Footnotes

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

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