Conversion of Postfix to Prefix expressionWhat is Postfix expression?A postfix expression is said to be an expression in which the operator appears after the operands. It can be written as: (operand) (operand) (operator) For example: If the expression is: (A+B) * (C+D) Firstly, operator precedence rules will be applied to the above expression. Since the parenthesis has higher precedence than the multiplication operator; therefore '+' will be resolved first, and the + operator will come after AB and CD shown as below: (AB+) * (CD+) Now, the multiplication operator will move after CD+ shown as below: AB+ CD+* What is Prefix Expression?A prefix expression is said to be an expression in which the operator appears before the operands. For example: If the expression is given as: (A+B) * (C+D) Firstly, operator precedence rules will be applied to the above expression. Since the parenthesis has higher precedence than the multiplication operator; therefore, the '+' operator will be resolved first, and the '+' operator will move before the operands AB and CD shown as below: (+AB) * (+CD) Now, the multiplication operator will move before the +AB shown as below: *+AB+CD Conversion of Postfix to Prefix expressionThere are two ways of converting a postfix into a prefix expression:
Conversion of Postfix to Prefix expression manually The following are the steps required to convert postfix into prefix expression:
Let's understand through an example. a b  c + First, we scan the expression from left to right. We will move '' operator before the operand ab. abc+ The next operator '+' is moved before the operand abc is shown as below: +abc Conversion of Postfix to Prefix expression using Stack The following are the steps used to convert postfix to prefix expression using stack:
Create an expression by concatenating two operands and adding operator before the operands. Push the result back to the stack.
Pseudocode for the conversion of Postfix to PrefixLet's understand the conversion of postfix to prefix expression using stack. If the Postfix expression is given as: AB + CD  *
The prefix expression of the above postfix expression is *+ABCD. Implementation of Postfix to Prefix conversion in C++Output
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