Using programming we have to learn how to implement various algorithms. In this article, we are going to implement infix to prefix, infix to postfix, prefix to infix, prefix to postfix, postfix to infix, and postfix to infix calculator using c programming. Let's discuss a little bit about infix, prefix, and postfix notation.

#### Infix notation:

Infix is a formate of operators placement where the operator is specified in between the two operands.

#### Example of infix notation:

**a+b**

#### Prefix notation:

In prefix, the operator is specified between the two operands.

#### Example of prefix notation:

**+ab**

#### Postfix notation:

Postfix notation is formate where the operator is specified after the two operands. This notation is also called Reverse Polish Notation.

#### Example of postfix notation:

**ad+**

~~So
we can say that the terms infix, prefix, and postfix tell us whether the
operator's go-between, before, or after the operands. ~~**alert-info**

Infix, Prefix, and Postfix conversion in C programming |

### Infix, Prefix, and Postfix conversion in C programming

The C program has 5 options to convert:

- Infix to Prefix
- Infix to Postfix
- Prefix to Infix
- Postfix to Prefix
- Postfix to Infix

Main Menu of Infix, Prefix, and Postfix convertor |

### Algorithm for converting an infix expression into postfix operation

1. Add “(“at the beginning and “)” at the end of an

infix expression Q.

2. Scan Q from left to right and repeat

Step 3 to step 6.

3 If an operand is encountered, add it into postfix P.

4. If a left parenthesis is encountered,

push it onto the stack S

5. If an operator op is encountered then,

(a) Repeatedly pop from stack S and add

it to postfix each operator which has

same precedence as or higher precedence than op.

(b) Add op to Stack S.

6. If the right parenthesis is encountered, then

(a) Repeatedly pop from stack S and add

it to postfix each operator until left parenthesis is encountered on stacks.

(b) Remove the left parenthesis.

#### Algorithm for evaluation of postfix string

1. Scan postfix P from left to right and repeat

Step 2 and 3 for each element of P until the

NULL character or other symbol is encountered.

2. If an operand is encountered then push it onto the stack.

3. If an operator op is encountered, then

(a) Remove the top elements of stack S where A is the

top element and B is the next top element

(b) Evaluate B op A

(c) Place the result back onto the stack S

(d) Return the top of the stack which is the required result for our calculation.

And finally the code we use to convert our infix equation to postfix and which is also able to find the result of the equation.

We are going to use the stack in C programming to implement Infix, Prefix and Postfix, conversion calculators.

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