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SMEE.java
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SMEE.java
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import java.util.Scanner;
/*
* Author: Emily Black
* Version: 1.0
* 2/19/17
*/
public class SMEE
{
public static double calculateExpr(String dataInput)
{
String num1 = ""; //Leftmost number from operator
String num2 = ""; //Rightmost number from operator
String expr = ""; //Holds full dataInput
double x = 0; //Holds num1 parsed into an int
double y = 0; //Holds num2 parsed into an int
double result = 0;
//If the label is empty OR ends with operator
if(dataInput.isEmpty() || dataInput.endsWith("*") || dataInput.endsWith("/") || dataInput.endsWith("+") || dataInput.endsWith("-") || dataInput.endsWith("."))
{
Exception e = new Exception("ERROR: Cannot compute: " + "'" + dataInput + "'" + ". " + "Cannot end dataInput in operator or null value.");
e.printStackTrace();
}
//If the label is NOT empty
else
{
while(dataInput.contains("*"))
{
int index = dataInput.indexOf("*");
//Look left of operator
for(int j = index-1; j >= 0; j--)
{
//While we haven't reached another operator
if(dataInput.charAt(j) != '*' && dataInput.charAt(j) != '/' && dataInput.charAt(j) != '+' && dataInput.charAt(j) != '-')
{
num1 += dataInput.charAt(j);
}
else if(dataInput.charAt(j) == '*' || dataInput.charAt(j) == '/' || dataInput.charAt(j) == '+' || dataInput.charAt(j) == '-')
{
break;
}
}
//Look right of operator
for(int k = index+1; k < dataInput.length(); k++)
{
//While we haven't reached another operator
if(dataInput.charAt(k) != '*' && dataInput.charAt(k) != '/' && dataInput.charAt(k) != '+' && dataInput.charAt(k) != '-')
{
num2 += dataInput.charAt(k);
}
else if(dataInput.charAt(k) == '*' || dataInput.charAt(k) == '/' || dataInput.charAt(k) == '+' || dataInput.charAt(k) == '-')
{
break;
}
}
num1 = new StringBuilder(num1).reverse().toString(); //We reverse num1 because we read it left to right, not right to left
x = Double.parseDouble(num1);
y = Double.parseDouble(num2);
result = x*y; //result contains result of operator
expr = num1 + "*" + num2;
dataInput = dataInput.replace(expr, Double.toString(result));
num1 = "";
num2 = "";
}
while(dataInput.contains("/"))
{
int index = dataInput.indexOf("/");
//Look left of operator
for(int j = index-1; j >= 0; j--)
{
//While we haven't reached another operator
if(dataInput.charAt(j) != '*' && dataInput.charAt(j) != '/' && dataInput.charAt(j) != '+' && dataInput.charAt(j) != '-')
{
num1 += dataInput.charAt(j);
}
else if(dataInput.charAt(j) == '*' || dataInput.charAt(j) == '/' || dataInput.charAt(j) == '+' || dataInput.charAt(j) == '-')
{
break;
}
}
//Look right of operator
for(int k = index+1; k < dataInput.length(); k++)
{
//While we haven't reached another operator
if(dataInput.charAt(k) != '*' && dataInput.charAt(k) != '/' && dataInput.charAt(k) != '+' && dataInput.charAt(k) != '-')
{
num2 += dataInput.charAt(k);
}
else if(dataInput.charAt(k) == '*' || dataInput.charAt(k) == '/' || dataInput.charAt(k) == '+' || dataInput.charAt(k) == '-')
{
break;
}
}
num1 = new StringBuilder(num1).reverse().toString(); //We reverse num1 because we read it left to right, not right to left
x = Double.parseDouble(num1);
y = Double.parseDouble(num2);
result = x/y; //result contains result of operator
expr = num1 + "/" + num2;
dataInput = dataInput.replace(expr, Double.toString(result));
num1 = "";
num2 = "";
}
while(dataInput.contains("+"))
{
int index = dataInput.indexOf("+");
//Look left of operator
for(int j = index-1; j >= 0; j--)
{
//While we haven't reached another operator
if(dataInput.charAt(j) != '*' && dataInput.charAt(j) != '/' && dataInput.charAt(j) != '+' && dataInput.charAt(j) != '-')
{
num1 += dataInput.charAt(j);
}
else if(dataInput.charAt(j) == '*' || dataInput.charAt(j) == '/' || dataInput.charAt(j) == '+' || dataInput.charAt(j) == '-')
{
break;
}
}
//Look right of operator
for(int k = index+1; k < dataInput.length(); k++)
{
//While we haven't reached another operator
if(dataInput.charAt(k) != '*' && dataInput.charAt(k) != '/' && dataInput.charAt(k) != '+' && dataInput.charAt(k) != '-')
{
num2 += dataInput.charAt(k);
}
else if(dataInput.charAt(k) == '*' || dataInput.charAt(k) == '/' || dataInput.charAt(k) == '+' || dataInput.charAt(k) == '-')
{
break;
}
}
num1 = new StringBuilder(num1).reverse().toString(); //We reverse num1 because we read it left to right, not right to left
x = Double.parseDouble(num1);
y = Double.parseDouble(num2);
result = x+y; //result contains result of operator
expr = num1 + "+" + num2;
dataInput = dataInput.replace(expr, Double.toString(result));
num1 = "";
num2 = "";
}
//While it does not start with - and contains atleast one -
while(dataInput.contains("-") && !dataInput.startsWith("-"))
{
int index = dataInput.lastIndexOf("-");
//Look left of operator
for(int j = index-1; j >= 0; j--)
{
//While we haven't reached another operator
if(dataInput.charAt(j) != '*' && dataInput.charAt(j) != '/' && dataInput.charAt(j) != '+' && dataInput.charAt(j) != '-')
{
num1 += dataInput.charAt(j);
}
else if(dataInput.charAt(j) == '*' || dataInput.charAt(j) == '/' || dataInput.charAt(j) == '+' || dataInput.charAt(j) == '-')
{
break;
}
}
//Look right of operator
for(int k = index+1; k < dataInput.length(); k++)
{
//While we haven't reached another operator
if(dataInput.charAt(k) != '*' && dataInput.charAt(k) != '/' && dataInput.charAt(k) != '+' && dataInput.charAt(k) != '-')
{
num2 += dataInput.charAt(k);
}
else if(dataInput.charAt(k) == '*' || dataInput.charAt(k) == '/' || dataInput.charAt(k) == '+' || dataInput.charAt(k) == '-')
{
break;
}
}
num1 = new StringBuilder(num1).reverse().toString(); //We reverse num1 because we read it left to right, not right to left
x = Double.parseDouble(num1);
y = Double.parseDouble(num2);
result = x-y; //result contains result of operator
expr = num1 + "-" + num2;
dataInput = dataInput.replace(expr, Double.toString(result));
num1 = "";
num2 = "";
}
//If it contains more than one - and starts with -
while(dataInput.indexOf("-") != dataInput.lastIndexOf("-") && dataInput.startsWith("-"))
{
int index = dataInput.lastIndexOf("-");
//Look left of operator
for(int j = index-1; j >= 0; j--)
{
//While we haven't reached another operator
if(dataInput.charAt(j) != '*' && dataInput.charAt(j) != '/' && dataInput.charAt(j) != '+' && dataInput.charAt(j) != '-')
{
num1 += dataInput.charAt(j);
}
else if(dataInput.charAt(j) == '*' || dataInput.charAt(j) == '/' || dataInput.charAt(j) == '+' || dataInput.charAt(j) == '-')
{
break;
}
}
//Look right of operator
for(int k = index+1; k < dataInput.length(); k++)
{
//While we haven't reached another operator
if(dataInput.charAt(k) != '*' && dataInput.charAt(k) != '/' && dataInput.charAt(k) != '+' && dataInput.charAt(k) != '-')
{
num2 += dataInput.charAt(k);
}
else if(dataInput.charAt(k) == '*' || dataInput.charAt(k) == '/' || dataInput.charAt(k) == '+' || dataInput.charAt(k) == '-')
{
break;
}
}
num1 = new StringBuilder(num1).reverse().toString(); //We reverse num1 because we read it left to right, not right to left
x = -x;
x = Double.parseDouble(num1);
y = Double.parseDouble(num2);
result = x-y; //result contains result of operator
expr = num1 + "-" + num2;
dataInput = dataInput.replace(expr, Double.toString(result));
num1 = "";
num2 = "";
}
//If the user just enters a random number, give them back that random number
if((dataInput.startsWith("-") || !dataInput.contains("-")) && !(dataInput.contains("*") && dataInput.contains("/") && dataInput.contains("+")))
{
result = Double.parseDouble(dataInput);
}
}
return result;
}
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
System.out.println("Enter your mathematical dataInput (using only *, /, +, -):");
String input = in.nextLine();
System.out.println("Result: " + calculateExpr(input));
in.close();
}
}