**Which Data Structure Is Used to Convert Postfix to Infix?**

When it comes to manipulating and converting data in programming, understanding how different data structures work is essential. One common task in this realm is converting postfix expressions to infix expressions. In this article, we will explore the data structure that is commonly used to accomplish this task.

## What is a Postfix Expression?

A postfix expression, also known as Reverse Polish Notation (RPN), is a mathematical notation in which operators are placed after their operands. For example, the infix expression “3 + 4” would be written in postfix as “3 4 +”. This notation eliminates the need for parentheses and allows for easy evaluation using stacks.

## The Stack Data Structure

To convert a postfix expression to an infix expression, we commonly use the stack data structure. A stack follows the Last-In-First-Out (LIFO) principle, where elements that are inserted last are the first ones to be removed.

To implement a stack, we can use an array or a linked list. Each element in the stack is referred to as a node. The two main operations performed on a stack are:

**Push:**Inserting an element onto the top of the stack.**Pop:**Removing an element from the top of the stack.

The idea behind using a stack for postfix to infix conversion is that we can store operators encountered in the postfix expression and retrieve them when needed based on their priority.

## The Algorithm

To convert a postfix expression to an infix expression using a stack, follow these steps:

- Create an empty stack.
- Iterate through each character in the postfix expression.
- If the character is an operand (number), push it onto the stack.
- If the character is an operator, pop two operands from the stack, construct an infix expression using the operator and operands, and push it back onto the stack.
- Repeat steps 3 and 4 until all characters in the postfix expression have been processed.
- The final infix expression will be stored on top of the stack.

This algorithm leverages the LIFO property of stacks to ensure that operators are applied to their respective operands in a correct order, resulting in a valid infix expression.

## Conclusion

In conclusion, when converting postfix expressions to infix expressions, we commonly use the stack data structure. The stack allows us to process operators based on their priority and construct a valid infix expression. By understanding how stacks work and implementing them effectively, we can perform this conversion efficiently within our programs.