Mathematical Expression Parsers in Java and C++
Basic Expression Parsing Click here for advanced expression parsing When writing your own calculator it is necessary to build a converter that can transform an input mathematical expression such as ( 1 + 8 ) – ( ( 3 * 4 ) / 2 ) , into a format that is more suited for evaluation by computers. When evaluating expressions such as the one above (known as “ infix notation "), that which appears simple and intuitive to us humans, is usually not so straightforward to implement in a programming language. The shunting-yard algorithm is a method for parsing mathematical expressions written in infix notation to Reverse Polish Notation (RPN) . The RPN notation is different to infix notation in that every operator (+, -, * etc) comes after the operands (numbers) and there are no parentheses (brackets). So ( 3 * 4 ) for example becomes 3 4 * . When given an input string in Reverse Polish Notation, it is then possible to employ a simple algorithm based around the use o...