iteration over several variables

[Saeid SSS]

Hello. I want to execute some instructions while iterating over all possible values for several variables. if the number of variables are few, I can write for loops inside eachother for this purpose. But here I have like 100 variables in a vector. and i might also change this number for another run. so that's not a practical solution... I wonder if there is an innovative way to do that?
Assume I'd like to compute sum(R1*R2*...*R n) for all Ri between 0 and r. Please don't simplify the equation, as that's not the real thing that I want to compute :-)

[Banfa]

I would suggest you write a function that given 1 set of variables returns the next set (or an end flag).

Then you can use the pseudo code

vector<> VariableSet;

DO
   // Perform operation on VariableSet

   HaltFlag = GetNextSet(VariableSet);

UNTIL HaltFlag == TRUE

[Saeid SSS]

Thank you!!!!!!!!!!!! !!!!!!!