Evaluate function?

[KcDan]

I'm working on a calculator for my shell and I cant find anywhere if there is a function that evaulates a string and turns it into a number, for example

"5+6-2" -> 9

[youresam]

somenumber = tonumber("5+6-2")

then, somenumber should equal 9, I think.

[KcDan]

I tried that earlier and it did not work, thanks though.

[ema]

hi,

Code: Select all

expression = "5+6-2"

script = "return " .. expression -- convert to LUA script
func, err = loadstring(script)
if err then
  -- syntax error
else
  result = func()    -- now result == 9
end

will work.

[KawaGeo]

Also, the following will work:

Code: Select all

script = "return 5+6-2"
result = assert(loadstring(script))()

Ref: Lua 5 Ref, page 40

Ema, you must have read PIL book well. :)

Hey, guys out there .. hint, hint

[KcDan]

Thanks a lot you two.