Expression Evaluation in python | What is Expression Evaluation |

Expression Evaluation in python | What is Expression Evaluation | 

Expression Evaluation –

Evaluate an expression represented by a string .expression can contain parentheses you can assume parentheses  are  well matched .for simplicity you can assume only binary operation allowed are + , - , * , & , / arithmetic. 

Expression can be written in one of three forms.

1) Infix Notation –

Operators are written between the operands they operate on

Example -> 3+4 Or A+b

2) Prefix Notation –

Operators are written before the operands.

Example -> +34 or +AB

3) Postfix Notation –

Operators are written after operands .

Example ->  34+     or      AB+

To simplify the evaluation of mathematical expression we need representation for the expression.

A representation in which the order the operators are performed is the order they are specified. Representation of string would allow for a single Left-to-Right scan of the expression string.

Expression precedence of operator is determine by BODMAS rule .

Consider Operation -> Addition , Subtraction, Multiplication, Division, Exponential.

We assume three level of precedence this is five binary operators in such notation.

1) Highest -> Exponent 

2) Next -> Multiplication and Division 

3) Lowest -> Addition and subtraction