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For my java Class I have to build a calculator using infix form including parentheses where necessary, and then its value.
I can use something like this
and the answer should be this:
For this assignment you may assume that all of the operators are binary, and are represented by the following symbols: P (plus for addition), M (minus for subtraction), D (division symbol for integer division), and T (times for multiplication).
Expert Answer
/*Source code is given below; it should be run from command promt:*/
import java.util.Arrays;
import java.util.Scanner;
import java.util.Stack;
public class RNPCalculator {
/**
* Checks if the input is operator or not
* @return true if operator
*/
private boolean isOperator(String c){
if(c.equals(“P”) || c.equals(“M”) || c.equals(“D”) || c.equals(“T”))
return true;
return false;
}
/**
* Converts any postfix to infix
* postfix String expression to be converted
* @return String infix expression produced
*/
public String convert(String[] token){
Stack<String> s = new Stack<>();
String result=””;
for(int i = 0; i < token.length; i++){
if(token[i].equals(“P”))
System.out.print(” “+”+”);
else if(token[i].equals(“M”))
System.out.print(” “+”-“);
else if(token[i].equals(“D”))
System.out.print(” “+”/”);
else if(token[i].equals(“T”))
System.out.print(” “+”*”);
else
System.out.print(” “+token[i]);
}
System.out.println(“n”);
for(int i = 0; i < token.length; i++){
String op=token[i];
if(isOperator(op)){
String b = s.pop();
String a = s.pop();
if(op.equals(“P”))
op=”+”;
if(op.equals(“M”))
op=”-“;
if(op.equals(“D”))
op=”/”;
if(op.equals(“T”))
op=”*”;
s.push(“(“+a+op+b+”)”);
}
else
s.push(“”+op);
}
result = s.pop();
return result;
}
public int evalRPN(String[] tokens) {
int returnValue = 0;
String operators = “PMTD”;
Stack<String> stack = new Stack<String>();
for(String t : tokens){
if(!operators.contains(t)){
stack.push(t);
}else{
int a = Integer.valueOf(stack.pop());
int b = Integer.valueOf(stack.pop());
int index = operators.indexOf(t);
switch(index){
case 0:
stack.push(String.valueOf(a+b));
break;
case 1:
stack.push(String.valueOf(b-a));
break;
case 2:
stack.push(String.valueOf(a*b));
break;
case 3:
stack.push(String.valueOf(b/a));
break;
}
}
}
returnValue = Integer.valueOf(stack.pop());
return returnValue;
}
public static void main(String[] args) {
RNPCalculator obj = new RNPCalculator();
//System.out.println(“Enter postfix expression:”);
//Scanner sc =new Scanner(System.in);
//String postfix = sc.nextLine();
//String[] token = postfix.split(“\s”);
//System.out.println(obj.convert(token));
//System.out.println(obj.evalRPN(token));
System.out.println(obj.convert(args));
System.out.println(obj.evalRPN(args));
}
}
/*output screenshot is given here*/
