问题
Okay, so I just recently got into lua and find myself stuck with the following:
I have the function peripheral.getNames() (which is a custom function)
it will return a table with the structure key,value, whereas key is always a number and starts from 1 and value will be what the function finds (it searches for devices connected to it)
In my example it creates a table which looks like this
1 herp
2 derp
3 monitor_1
4 morederp
I can print the values with the following
local pgn = peripherals.getNames()
for key,value in pairs(pgn) do
setCursorPos(1,key)
write(value)
end
end
this will output the corresponding value of the table at key on my display like this
herp
derp
monitor_1
morederp
now, I try to filter my results so it only prints something if value contains 'monitor'
I tried to achive this with
for key,value in pairs(pgn) do
if string.match(value, monitor) then
#dostuff
end
end
but it always returns 'bad argument: string expected, got nil' so obviously string.match either does not accept 'value' or, value is not a string so i tried converting value first
for key,value in pairs(pgn) do
value = tostring(value)
if ....
#dostuff
end
end
but it still throws the same error
Do any of you have an idea how i might either get string.match to accept 'value' or if there is another method to check the contents of 'value' for a pattern while in this for loop?
回答1:
The error message is talking about the variable monitor
, which is not defined and so has a nil value.
Try string.match(value, "monitor")
.
来源:https://stackoverflow.com/questions/25252653/print-value-from-a-lua-table-if-pattern-matches