减法程序中的一个非常简单的错误

Question

I am facing a very simple error in the following program at the last print statement. But I dont know the exact reason behind it. Even the logic is correct and syntax too.

Please let me know the exact reason for the error.

Thanks

import java.util.Scanner;
public class main
{
    public static void main(String args[])
    {
        int c,d;
        Scanner s = new Scanner(System.in);
        System.out.print("Enter the first number : ");
        c = s.nextInt();
        System.out.print("Enter the second number : ");
        d = s.nextInt();

        System.out.println("The sub is : "+ c-d);

    }
}

Answer 1

You need parentheses around the subtraction:

System.out.println("The sub is : " + (c - d));

This is because without parentheses, the + and - operators have the same priority and associate left-to-right. So the compiler tries to parse it as if it were written:

System.out.println(("The sub is : " + c) - d);

The first part is okay and is an expression that produces a String result. Unfortunately, there is then no way to apply the - operator to an expression where the left side is a String and the right side is an int .

Answer 2

that's because, you are trying to do string concatenation, as your first operand is a string.

try this:

System.out.println("The sub is : "+ (c-d));

notice that (cd) in brackets.

compiler would complain that - operator is un-defined for string and int.

The operator - is undefined for the argument type(s) String, int

Note that the Sub is:+ c the result would be a string. now

`Sub is:+ c` - d;
^^String     - int

Answer 3

use

System.out.println("The sub is : "+ (c-d));

instead of

System.out.println("The sub is : "+ c-d);

and check if its working now.