Could anyone make original functions for this code?

Also a design document/flowchart

These is the requirements:

Implement a program that will use a stack structure to check for correct placement of parentheses in an algebraic expression. Allow the use of ( ) [ ] { } characters as grouping symbols. Make sure that an error is reported for an expression of a form (...]. In addition report other possible parentheses-related errors (too many levels, too many right paren., too many left parens.). Make sure to use 'silent error reporting' (and report any possible errors outside the main scanner loop).