Question

Write a class PostFix that has one method covert that converts an infix expression (as a string input) to a postfix. Then Test it in a different class. code in java.

Answer 1

import java.util.Stack;

class PostFix{
   // Higher returned value means higher precedence
static int Prec(char ch)
{
switch (ch)
{
case '+':
case '-':
return 1;

case '*':
case '/':
return 2;

case '^':
return 3;
}
return -1;
}

// The main method that converts given infix expression
public static String infixToPostfix(String exp)
{
String result = new String("");
  
Stack <Character>stack = new Stack<>();
  
for (int i = 0; i<exp.length(); ++i)
{
char c = exp.charAt(i);
  
// If the scanned character is an operand, add it to output.
if (Character.isLetterOrDigit(c))
result += c;

// If the scanned character is an '(', push it to the stack.
else if (c == '(')
stack.push(c);
  
else if (c == ')')
{
while (!stack.isEmpty() && stack.peek() != '(')
result += stack.pop();
  
if (!stack.isEmpty() && stack.peek() != '(')
return "Invalid Expression"; // invalid expression   
else
stack.pop();
}
else
{
while (!stack.isEmpty() && Prec(c) <= Prec(stack.peek()))
result += stack.pop();
stack.push(c);
}

}

// pop all the operators from the stack
while (!stack.isEmpty())
result += stack.pop();

return result;
}
  
}

public class TestPostFix {
   public static void main(String[] args) {
       System.out.println(PostFix.infixToPostfix("a+b*(c^d-e)^(f+g*h)-i"));
   }
}

NOTE : PLEASE COMMENT BELOW IF YOU HAVE CONCERNS.

I AM HERE TO HELP YOUIF YOU LIKE MY ANSWER PLEASE RATE AND HELP ME IT IS VERY IMP FOR ME