Class Demo

stack/postfix/Demo.java:10–132

import java.util.Scanner;

public class Demo 
{
	public static void main(String[] args) 
	{
		String infix;
			
		Scanner scan = new Scanner(System.in);	
		  
		System.out.print("Enter infix expression : ");
		infix = scan.nextLine();
		
		String postfix = infixToPostfix(infix);
		
		System.out.println("Postfix expression is : " + postfix);
		
		System.out.println("Value of expression : " + evaluatePostfix(postfix));
		
		scan.close();
	}
	
	public static String infixToPostfix(String infix)
	{
		String postfix = new String();
		
		StackChar st = new StackChar(20);
				
		char next,symbol;
		for(int i=0; i<infix.length(); i++)
		{
			symbol=infix.charAt(i);
			
			if(symbol==' ' || symbol=='\t') /*ignore blanks and tabs*/
				continue;
			
			switch(symbol)
			{
				case '(':
					st.push(symbol);
					break;
				case ')':
					while((next=st.pop())!='(')
						postfix = postfix + next;
					break;
				case '+':
				case '-':
				case '*':
				case '/':
				case '%':
				case '^':
					while( !st.isEmpty() &&  precedence(st.peek())>= precedence(symbol) )
						postfix = postfix + st.pop();
					st.push(symbol);
					break;
				default: /*operand*/
				     postfix = postfix + symbol;
			}
		}
		while(!st.isEmpty())