How to convert a string to an integer?

[cook]

As the title says, making a script that returns the Entity's 6th letter(which is a number) that is being interacted with to a string using SetLocalVarString("bigman", StringSub(asEntity, 5, 1));, but that didn't work. Couldn't use LocalVarInt bigman either. I believe I need a way to convert it to an integer to make use of it like so SetEntityActive("crowbar_joint_"+"bigman", true);

It's for a crowbar that works on all doors script so I don't have to copy like 30 lines of code 9 times, if anyone could think of a easier way to do it please tell me.

Also, while I am here, what is the actual definition of a signature?