How to write a function that recognises unbalanced brackets

Question

I am trying to write a function that checks if a syntax is correct or not. If it is correct it returns \'ok\' else it returns the index of the error. So far my code works if

Answer 1

An algorithm for doing this is, find an opening symbol, push it to a stack (or array, whatever). Find another opening symbol, push it to a stack. Find a closing symbol that matches the top of the stack, pop the opening symbol off the stack. Find a closing symbol that doesn't match the top of the stack, you found an error. Find a closing symbol and there's nothing on the stack, you found an error. Get to the end and still have symbols on the stack, you found an error.