Keithley System SourceMeter 2601B, Reference Manual

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Section 6: Instrument programming Series 2600B System SourceMeter® Instrument Reference Manual
6-14 2600BS-901-01 Rev. B / May 2013
Variable types
Variables can be one of the following types.
Variable types and values
Variable type returned Value Notes
"nil" not declared The type of the value
nil
, whose
main property is to be different from
any other value; usually it represents
the absence of a useful value.
"boolean" true or false Boolean is the type of the values
false
and
true
. In Lua, both
nil
and
false
make a condition
false
; any other value makes it
true
.
"number" number All numbers are real numbers; there
is no distinction between integers
and floating-point numbers.
"string" sequence of words or
characters
"function" a block of code Functions perform a task or compute
and return values.
"table" an array New tables are created with { }
braces. For example,
{1, 2, 3.00e0}.
To determine the type of a variable, you can call the
type()
function, as shown in the examples
below.
The output you get from these examples may vary depending on the data format that is set.
Example: Nil
x = nil
print(x, type(x))
nil nil
Example: Boolean
y = false
print(y, type(y))
false boolean
Example: String and number
x = "123"
print(x, type(x))
x = x + 7
print(x, type(x))
123 string
Adding a number to x forces its type to
number.
1.30 number