如何在Lua中正确地重新分配变量？

Question

I am writing a user program for a simulation software. There is a variable called adj_elect05. The following chunk of code gets called over and over again. Each time it gets called, I want adj_elect05 (which has a numeric value) to be incremented by a certain amount, and then have that amount written to a file. This is the code that works:

increment = -10

adj_elect05 = adj_elect05 + increment

oct_voltages = io.open(O_V, "a+")
oct_voltages:write("\n", adj_elect05) 
oct_voltages:close ()

In the file I get a list of numbers: -10, -20, -30, and so on. The problem is I need to give adj_elect05 a generic name so that it can be changed later on without having to change every instance it shows up so I wrote:

increment = -10
octupole_v = adj_elect05

octupole_v = octupole_v + increment

oct_voltages = io.open(O_V, "a+")
oct_voltages:write("\n", octupole_v) 
oct_voltages:close ()

With this, I get -10 written to the file for ever time the code runs, rather than having it decrease by ten every time. What am I doing wrong?

Answer 1

What you need is to use local variable:

local increment = -10
local octupole_v = adj_elect05
octupole_v = octupole_v + increment

By default variables are considered global (unlike Python).