Infix to Postfix using array

[Franneldort]

Hello all!

I have an assignment to convert an infix expression in to postfix and I have to use an array rather than an actual stack, which I believe is the typical to do this process. I keep running into a problem when parentheses are in the expression and the array seems to replace operators with parentheses in the array and I cannot figure out why.

Specifically, when it comes to the second '(' sign, it replaces the '*' sign with it in the array.

The Expression I'm reading is, "(A*(B+C)".

This is my first post so let me know if I'm missing anything or if anyone needs anymore information. Thank you for any help!

// Translates arithmetic expressions (infix) into postfix expressions.  Checks for 
// parenthetical correctness.  Implements a user-defined stack.  
import java.util.*;
import java.io.*;

public class Main {

	// Initialize
	private static String output = "";
	private static String input = "";
	private static int top_ptr = -1;
	static char[] emu_stack = new char[9]; // Emulate a stack using a char
	// array
	
	public Main(String in)
	{
		 input = in;
		
	}

	public static void main(String[] args) throws IOException {
		
		// change to asking for
		// input file name
		// Initialize
		
			Main the_translation = new Main(input);
		File file = new File("C:\\Program Files\\first_input.txt");
		BufferedReader reader = null;

		reader = new BufferedReader(new FileReader(file));
		input = reader.readLine();
		output = the_translation.translation();
			
	//readInput();
	//print user input first!!  goes here
	System.out.println(output);

	}

	public  void readInput() throws IOException // later make sure to
	// change to asking for
	// input file name
	// Initialize
	{
	File file = new File("C:\\Program Files\\first_input.txt");
	BufferedReader reader = null;

	reader = new BufferedReader(new FileReader(file));
	input = reader.readLine();
	translation();
	}

	public  String translation() throws IOException

	{
		
		 String test = "(A*(B+C))";
		char ch = 0;
		for (int i = 0; i < test.length(); i++) {
			 ch = test.charAt(i);
			if(ch == ';')
			{
			System.out.println("All Done!");
			break;
			}
			System.out.println("for ch: " + ch);
			System.out.println("contents of stack: " + Arrays.toString(emu_stack));
			switch (ch) {
			
			default:
				output = output + ch;
				
				break;
				
			case '+':
			case '-':
				if (top_ptr == -1)
				{
					emu_stack[++top_ptr] = ch;
					break;
				}	
				else
				{
				got_operator(ch, 1, top_ptr);
				break;
				}
			case '*':
			case '/':
				if (top_ptr == -1)
				{
					emu_stack[++top_ptr] = ch;
					System.out.println("check");
					break;
				}	
				else
				{
				got_operator(ch, 2, top_ptr);
				break;
				}
			case '^':
				if (top_ptr == -1)
				{
					emu_stack[++top_ptr] = ch;
					break;
				}	
				else
				{
				got_operator(ch, 3, top_ptr);
				break;
				}
			case '(':
				
				emu_stack[++top_ptr] = ch;
				break;
			case ')':
				got_parenentheses(ch, top_ptr);
				break;
		
			}

		}	while( top_ptr != -1)
		{	
			if(emu_stack[top_ptr] == '(')
			{
				System.out.println("( was hit");
				top_ptr--;
				
			}
			else
			output = output + emu_stack[top_ptr--];
			
				
				
		}
		return output;

	}//end translation()

	public  void got_parenentheses(char ch, int top_ptr) {
		top_ptr++;
		while (top_ptr != -1) {
			System.out.println("contents of stack end: " + Arrays.toString(emu_stack));
			 char chx = emu_stack[top_ptr--];
			
			if (chx == '('){ 
			
				System.out.println("paren why");
				
				 break;
			}	
			else
			
				
				output = output + chx;
				System.out.println("output = " +output);

		}
	}

	public static void got_operator(char top_operator , int precedence, int top_ptr) {
		
	
		while (top_ptr != -1)

		{
			char top_op_popped = emu_stack[top_ptr--];
			{
				if (top_op_popped == '(') 
				{
					emu_stack[++top_ptr] = top_op_popped;
					break;
				} 
				else 
				{
					int precedence2 = 0;

					if (top_op_popped == '+' || top_op_popped == '-') {
						precedence2 = 1;
					} else if(top_op_popped == '*' || top_op_popped == '/')
						precedence2 = 2;
						else if (top_op_popped == '^')
						precedence2 = 3;
					if (precedence2 < precedence) {
						top_op_popped = emu_stack[++top_ptr];
						break;
					} else {
						output = output + top_op_popped;
						
						
					}
				}
			}//end else
			
		}//end while
			
			emu_stack[++top_ptr] = top_operator;
	}

}