If i add the first line as suggested, i get the below error

lua: main.lua:$1$: attempt to index global $\text{'}$op$\text{'}($a nil value$)$

stack traceback:

main.lua:$1$: in main chunk

$[$C$]$: $?$

i also see these in my comments$/$dialog box on runtime

$---$ Program output $---$

lua: main.lua:$36$: bad argument #$2$ to 'tonumber' $($base out of range$)$

stack traceback:

$[$C$]$: in function 'tonumber'

main.lua:$36$: in main chunk

$[$C$]$: $?$

Enter command:

so i have commented it out inorder to compile the program, however i am still not geting the correct program output.

just for reference, this is the grid which i am assuming is part of grid.txt$.$ the $0-4$ i am assuming is being omitted but i just used it as a point of reference for you

$01234$

$00\mathrm{.}00\mathrm{.}20\mathrm{.}40\mathrm{.}50\mathrm{.}3$

$10\mathrm{.}20\mathrm{.}00\mathrm{.}00\mathrm{.}70\mathrm{.}8$

$20\mathrm{.}40\mathrm{.}00\mathrm{.}00\mathrm{.}60\mathrm{.}0$

$30\mathrm{.}50\mathrm{.}70\mathrm{.}60\mathrm{.}00\mathrm{.}9$

$40\mathrm{.}30\mathrm{.}80\mathrm{.}00\mathrm{.}90\mathrm{.}0$

For numbering purposes the rows and values are indexed on a $0-$index basis $($i$.$e$.$ the

first row is row $0$ and the first column is column $0)$

can i please ask that you check the outputs before responding back, as this is the $6$th iteration of the same question that i have been asking for assistance on$.$ i am really appreciative of your help and guidance but i feel we are stuck on question$1$ and without me$/$us getting it correct, i am not sure how to even attempt the more complez questions being asked. i hope you can understand where i am coming from by requesting this and if possible you run the code in a compiler.

$--$local file $=$ op$.$open$($filename $,"$r$")$

function loadgrid$($filename$)$

local file $=$ io$.$open$("$grid$.$txt$","$r$")$

if not file then

print$("$Error: unable to open file"$)$

return

end

local grid $=\{\}$

for line in file:lines$()$ do

local row $=\{\}$

for num in line:gmatch$("\%$d$+")$ do

table.insert$($row$,$ tonumber$($num$))$

end

table.insert$($grid$,$ row$)$

end

file:close$()$

return grid

end

function areneighbours$($city$1,$ city$2,$ grid$)$

if city$1>=0$ and city$1<$ #grid and city$2>=0$ and city$2<$ #grid$[$city$1+1]$ then

return grid$[$city$1+1][$city$2+1]>0$

else

return false

end

end

local grid $=$ loadgrid$("$grid$.$txt$")$

while true do

io$.$write$("$Enter command: $")$

local command $=$ io$.$read$()$:lower$()--$ Convert to lowercase for case$-$insensitivity

if command $==$ "areneighbours" then

local city$1,$ city$2=$ tonumber$($io$.$read$("*$n$")),$ tonumber$($io$.$read$("*$n$"))$

if city$1$ and city$2$ then

print$($areneighbours$($city$1,$ city$2,$ grid$))$

else

print $("$Invalid input for cities. Please enter valid numbers"$)$

end

elseif command $==$ "exit" then

break

else

print$("$Unknown command"$)$

end

end

Enter command: areni eighbours

$0$

$1$

false

Enter command: Unknown command

Enter command: areneighbours

$1$

$32$

false

Enter command: Unknown command

Enter command:

THE EXPECTED RESULTS SHOULD BE AS below

Expected output on test data with input $(0,1)$: Yes

Expected output on test data with input $(1,2)$: No

Expected output on test data with input $(3,4)$: Yes

Expected output on test data with input $(0,4)$: Yes