Question about "autodetecting" variables.

[Jiroxys7]

I believe im fairly familiar with using the serverside <=> clientside stuff. didnt know the difference between temp.var and this.var though =3

so if i want to create an important clientr.var, i should do something like this?:

example:

PHP Code:

function onActionServerSide(cmd) {
  if (temp.cmd == "calc_math") {
    doMakeMathVar_S();
  }
}

function doMakeMathVar_S(){
   clientr.num = this.num1 + this.num2;
}

//#CLIENTSIDE

function doMakeMathVar_C() {
  this.num1 = 1;
  this.num2 = 2;
  triggerServer("weapon", this.name, "calc_math", this.num1, this.num2);
} 


clientr.num should equal 3.

now, I'm wondering though, are people able to hack and edit this.num1 and this.num2 to change the outcome of clientr.num? or is it just harder to hack compared to client.vars?