title: How to write an evaluator for a string like "(1+3 * ( 5 / 4)) and get a numeric result
body: <p>this is a interview question
  i am confused about its solution, i am thinking that i need stacks to push and pop these operators and operands,
  but do i need two stacks, one for operator and one for operands? or would just one stack do?i think we need two stacks but is there any way to solve using one stack?</p>
  
  <p>also i am bit confused how would this work, each time i get an operator i would pop two of my topmost operands and push the result in the operand stack</p>
  
  <p>the preferance is brackets first,then divide,multioply and last subtraction and then addition</p>
  
  <p>but how to check when to pop the two operands and do the necessary arthimetic  operation?</p>