Converting from infix to postfix in python | how to convert from infix to postfix in python |
The Expression we ( human being ) write are called
infix expression as the operatiors come in between in operands .
A + B this is infix expression because the operator
‘+’ comes between operands A and
B .
To evaluate expression manually infix notation is
helpful as it is easily understandable by human brain.
But infix expression are hand to parse in a computer
program hence it will be difficult to evaluate expression using infix notation.
To reduce the complexity of expression evaluation Prefix
or Postfix expression are used in computer programs.
In Postfix expression , operators comes after the
operands , below are an infix and respective postfix expression .
A+B -> AB+
 |
| Conversation from infix to postfix |
Steps for converting infix expression into postfix
expression.
1. Accept
infix expression as a string exp
2. For
i is a alphabet or digit:
Append
it to the postfix expression
Else
if I is ‘ ( ‘ :
Push
‘ ( ‘ is the stack
Else
if i is ‘ ) ‘ :
·
Pop the element from the stack and append
it postfix expression until we get ‘ ) ‘ on top of the stack.
·
Pop ‘ ( ‘ from the stack and don’t add it
in postfix expression .
Else if i is in ‘ */+- ‘ :
if stack is empty or top
of the stack is ‘ ( ‘ :
push the
operator in the stack.
Else :
Pop
the element from the stack and continue this
until the operator on the top of the stack has same or less residence then
the i. i.e ( stack operator higher
precedence than operator looking at then pop it and place at postfix expression
.
Else
: push i in
stack .
3. Once
we scanned exp completely start popping
the element from the stack and appending them to postfix expression .
The Conversion from infix to postfix show in following
table.
1) A
+ B * C – D * E
2) A
*( B + C)
1]
Post a Comment