Why do we need Prefix and Postfix notations?

Prefix Notation:

Prefix notation is the notation in which operators are placed before the corresponding operands in the expression.

Example:

Infix notation: A + B    
Prefix notation: +AB

Postfix Notation:

Postfix notation is the notation in which operators are placed after the corresponding operands in the expression.     

Example: 

Infix notation: A + B    
Postfix notation: AB+

Need of Prefix and Postfix Notations:

• Prefix notations are needed when we require operators before the operands while postfix notations are needed when we require operators after the operands.
• Prefix notations are used in many programming languages like LISP.
• Prefix notations and Prefix notations can be evaluated faster than the infix notation.
• Postfix notations can be used in intermediate code generation in compiler design.
• Prefix and Postfix notations are easier to parse for a machine.
• With prefix and postfix notation there is never any question like operator precedence.
• There is no issue of left-right associativity.

Advantages of Postfix over Prefix Notations:

• Postfix notation has fewer overheads of parenthesis. i.e., it takes less time for parsing.
• Postfix expressions can be evaluated easily as compared to other notations.