picking variables for dependencies in a loop

Hi everyone! i want to check each variable in a loop whether the variables are going to be used in the next iteration or not?i mean whether the variables are changing values and using the in the next iteration!so i need to pick each of the variables in the loop to check ....so how can i pick and read them as whether they are changing values ,using in the next iteration! i want some help of syntax i guess!so please help me out um starving!

[Jan]

Did you choose the tag "code" and if so, why?

The question is not clear. Could you add a minimal example by editing the question - not as comment or answer?