Question(Data Structures)

[PugoOfficial]

Can someone tell me what is hierarchy of operators (in infix,prefix,postfix notations)

[KuroSetsuna29]

For infix notation, (eg. (1 + 1) * 2)

It follows the standard "BEDMAS" (although that is technically not correct either), but keeping it simple it is: Brackets, Exponents, Division, Multiplication, Addition, and then Subtraction. If you wanted to explicitly apply the order of operations, you would need to wrap brackets as opposed to the other two notations.

 

 

For prefix notation, also known as Polish Notation, (eg. * + 1 1 2)

It is like a stack of operations, from inside out. In essence it is in this format: <operator> <value1> <value2>

Where each value can be another polish notation expression.

 

For example: * + 1 1 2

= * (+ 1 1) (2)

= * (2) (2)

= 4

 

Note: (the parenthesis are not required, just easier to visually see what is going on)

 

This can seem very confusing if not use to the notation, but advantage is it leave very little ambiguity of which operation applies first, and thus does not require any parenthesis.

 

 

For postfix notation, also known as Reverse Polish Notation, (eg. 1 1 + 2 *)

As the name suggests, it is the opposite of Polish Notation where the operator goes after the two values instead of before.

 

 

Edited March 6, 2015 by KuroSetsuna29