Keithley 2450 - Page 512

Model 2450
Interactive SourceMeter® Instrument Reference Manual Section 7:
Introduction to TSP operation
2450-901-01 Rev. B/September 2013 7-21
Loop control
If you need to repeat code execution, you can use the Lua while, repeat, and for control
structures. To exit a loop, you can use the break keyword.
While loops
To use conditional expressions to determine whether to execute or end a loop, you use while loops.
These loops are similar to Conditional branching (on page 7-19
) statements.
while expression do
block
end
Where:
• expression is Lua code that evaluates to either true or false
• block consists of one or more Lua statements
The output you get from this example may vary depending on the data format settings of the
instrument.
Example: While
list = {
"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
6 Six
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.