Passing arguments into Lua

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7

To pass arguments into Lua, the script name and arguments must be enclosed within double quotes. The arguments are stored within the arg variable in Lua, which is a table of strings.

The example below shows how to iterate through the arguments and demonstrates some of the implications of the fact that the arguments are strings.

-- Print the script name

print(string.format('Script Name: "%s"',arg[0]))

FormatString = '%-10s%-10s%-15s%-15s'

print(string.format(FormatString,'Arg#','Type','String','Number'))

-- Iterate through the arguments

Sum = 0

NumberOfTwenties = 0

for i = 1,4 do

-- Print some information about the argument

-- NOTE: The type of these arguments is always "string"

print(string.format(FormatString,i,type(arg[i]),arg[i],tonumber(arg[i])))

-- Check if the string represents a number

if (tonumber(arg[i]) ~= nil) then

-- If the string represents a number, Lua will automatically

-- convert the string to a number for arithmetic

Sum = Sum + arg[i]

end

-- Since the arg values are always of type "string"

-- a direct comparison with a number will always fail

if (arg[i] == 20) then

NumberOfTwenties = NumberOfTwenties + 1

end

print('')

print(string.format("Sum of Number Arguments: %d",Sum))

print(string.format("Number of 20s found: %d",NumberOfTwenties))

Here is how to call this script using the LUA command. Note how the string "20" is not considered equal to the number 20.

lua prompt "scriptargs.lua 1 20 Hello 300"

<OK

Script Name: "scriptargs.lua"

Arg# Type String Number

1 string 1 1

2 string 20 20

3 string Hello nil

4 string 300 300

Sum of Number Arguments: 321

Number of 20s found: 0