6: Instrument programming  Series 2600B System SourceMeter® Instrument 
 
6-22  2600BS-901-01 Rev. B / May 2013 
 
Example: While 
 
   "One", "Two", "Three", "Four", "Five", "Six"} 
print("Count list elements on numeric index:") 
element = 1 
while list[element] do 
   print(element, list[element]) 
   element = element + 1 
end 
This loop exits when list[element] 
= nil. 
Output: 
Count list elements on 
   numeric index: 
1   One 
2   Two 
3   Three 
4   Four 
5   Five 
 
 
 
Repeat until loops 
To repeat a command, you use the repeat ... until statement. The body of a repeat statement 
always executes at least once. It stops repeating when the conditions of the until clause are met. 
repeat 
 block 
until expression 
Where: 
•  block consists of one or more Lua statements 
•  expression is Lua code that evaluates to either true or false 
The output you get from this example may vary depending on the data format settings of the 
instrument. 
 
Example: Repeat until 
 
   "One", "Two", "Three", "Four", "Five", "Six"}
print("Count elements in list using repeat:") 
element = 1 
repeat 
   print(element, list[element]) 
   element = element + 1 
until not list[element] 
Count elements in list 
   using repeat: 
1  One 
2  Two 
3  Three 
4  Four 
5  Five 
 
 
 
For loops 
There are two variations of for statements supported in Lua: numeric and generic. 
In a for loop, the loop expressions are evaluated once, before the loop starts. 
The output you get from these examples may vary depending on the data format settings of the 
instrument.