table to math

[BarnD]

Lets say if i have a table with "1, 9, +, 5, *, 1", is there some sort of way that I could get them out of the table and then do the maths "19+5*1"?

[TechnoCat]

Parse it into Reverse Polish Notation via Stunting-Yard algorithm
I've done it in the past with 2 stacks. One for numbers, one for operations.
Pop one from operation, two from numbers. Perform calculation, push back on stack, continue.

[slime]

Something like

Code: Select all

local mathstr = table.concat(mathtbl)
local sum = loadstring("return "..mathstr)()

might work.

[TechnoCat]

easy solution

http://pastie.org/1831669

are-you-wizard.png (77.55 KiB) Viewed 2165 times

[BarnD]

That way works like a charm, thanks.
Was busy reading "Reverse Polish notation" to notice that an easy way got posted. Thanks for such quick replies too.
EDIT: fail spelling is fail.. but is now fixed :/

[sharpobject]

Something like

Code: Select all

local mathstr = table.concat(mathtbl)
local sum = loadstring("return "..mathstr)()

might work.

Depending on how trusted this string is, you might not want to do that. If the string came from another player over the network, the other player could send you something like {"(function() love.update = nil return 7 end)()"}. This seems to be for a calculator that builds the string locally, so it should be fine.

[BarnD]

Depending on how trusted this string is, you might not want to do that. If the string came from another player over the network, the other player could send you something like {"(function() love.update = nil return 7 end)()"}. This seems to be for a calculator that builds the string locally, so it should be fine.

Yeah it was for a calculator, http://love2d.org/forums/viewtopic.php?f=5&t=2890