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Thread: Want to decipher a bit of code (pretty new to java)

  1. #1
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    Default Want to decipher a bit of code (pretty new to java)

    Hi guys! I needed help deciphering a section of my code. I found it online and got a little help from my friends, but I don't fully understand what it means. My code basically takes in an input from the user in the form mx+b, and then asks for x. The program then solves for x. I need help deciphering section 3 of my code.

     
    import java.util.Scanner;
     
    class Main {
      public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        //1
        String xExpression;
        System.out.println("Write an expression in mx+b form (eg. 2x+10)");
        xExpression = sc.nextLine();
     
    //2 
        int m = Integer.valueOf(xExpression.substring(0,xExpression.indexOf('x')));
        //System.out.println(m);
     
    //3
        int index=0, num=0;
        char sign='+';
     
        for (int i=xExpression.indexOf('x');i<xExpression.length();i++) {
          if (xExpression.charAt(i)=='+' || xExpression.charAt(i) == '-') {
            sign = xExpression.charAt(i);
            index=i;
            num = Integer.valueOf(xExpression.substring(index));
            //System.out.println(num);
          }
        }
        System.out.println(num);
     
    //4
        System.out.println("Enter x");
        int x = sc.nextInt();
     
        if (sign=='+') {
          System.out.println(m*x+num);
        } else if (sign=='-') {
          System.out.println(m*x-num);
        }
      }
    }

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Want to decipher a bit of code (pretty new to java)

    Can you ask some specific questions about the source statements in section 3 that you are having problems with?

    What did the print statements print before they were commented out?

    If you have questions about what any of the expressions do, add a print statement that prints out the results of when that expression is executed.
    If you don't understand my answer, don't ignore it, ask a question.

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