Infix to Prefix (Conversion, Evaluation, Code)
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The document summarizes an assignment on converting infix to prefix notation, evaluating infix expressions, and providing pseudocode to perform the conversion. It includes an example infix expression converted to prefix notation, evaluates the expression to verify the conversion is correct, and provides pseudocode that uses a stack to pop operators and operands off an infix string into a prefix notation string.
![Arr = (Infix Expression)
Set loop_counter to length_ of_ Arr
do
character = arr[loop_counter]
if character is operator
push character to prefix_stack
if character is ‘)’
push character to stack
if character is ‘(’
do
pop character and push it to prefix_stack
until character equals ‘(‘
if character is operator
if character_precedence is greater OR is equal to stack[top]_ precedence
push to stack
else
do
pop from stack and push to prefix_stack
until condition satisfices
loop_counter = loop_counter - 1
While loop_counter IS NOT EQUAL to 0
Pop out prefix_stack and display each element](https://image.slidesharecdn.com/infixtoprefix-130421063214-phpapp02/85/Infix-to-Prefix-Conversion-Evaluation-Code-5-320.jpg)
Infix to Prefix (Conversion, Evaluation, Code)
- 1. DATA STRUCTURES ASSIGNMENT # 2 “Infix to Prefix Conversion, Evaluation and Pseudo code” SUBMITTED TO: Zaheer Sani SUBMITTED BY: Ahmed Khateeb SP12-BCS-028 BSCS – IIIC Department of Computer Science
- 2. A) CONVERSION INFIX EXPRESSION TO PREFIX. B) EVALUATION OF INFIX EXPRESSION (AND VERIFICATION). C) PSEUDO CODE TO CONVERT INFIX TO PREFIX PART A - Let have an Infix Expression ( (A+B) * (C+D) / (E-F) ) + G - Reading Expression from “right to left” character by character. - We have Input, Prefix_Stack & Stack. - Now converting this expression to Prefix. Input Prefix_Stack Stack G G (empty) + G + ) G + ) ) G + ) ) F GF + ) ) - GF + ) ) - E GFE + ) ) - ( GFE- + ) / GFE- + ) / ) GFE- + ) / ) D GFE-D + ) / ) + GFE-D + ) / ) + C GFE-DC + ) / ) +
- 3. ( GFE-DC+ + ) / * GFE-DC+ + ) / * ) GFE-DC+ + ) / * ) B GFE-DC+B + ) / * ) + GFE-DC+B + ) / * ) + A GFE-DC+BA + ) / * ) + ( GFE-DC+BA+ + ) / * ( GFE-DC+BA+*/ + (empty) GFE-DC+BA+*/+ (empty) - Now pop-out Prefix_Stack to output (or simply reverse). Prefix expression is + / * + A B + C D – E F G PART B
- 4. - First I’m assigning values to all operands. A = 14 B = 12 C = 10 D = 8 E = 6 F = 4 G = 2 - Evaluating Infix expression using above values. ( (14+12) * (10+8) / (6-4) ) + 2 ( 26 * 18 / 2 ) + 2 ( 468 / 2 ) + 2 ( 234 ) + 2 236 - Evaluating Infix expression using above values. + / * + 14 12 + 10 8 - 6 4 2 (14+2 & 10+8 & 6-4) + / * 26 18 2 2 (26 * 18) + / 468 2 2 (468 / 2) + 234 2 (234 + 2) 236 - Both are same, so our conversion is correct! PART C
- 5. Arr = (Infix Expression) Set loop_counter to length_ of_ Arr do character = arr[loop_counter] if character is operator push character to prefix_stack if character is ‘)’ push character to stack if character is ‘(’ do pop character and push it to prefix_stack until character equals ‘(‘ if character is operator if character_precedence is greater OR is equal to stack[top]_ precedence push to stack else do pop from stack and push to prefix_stack until condition satisfices loop_counter = loop_counter - 1 While loop_counter IS NOT EQUAL to 0 Pop out prefix_stack and display each element