Shorthand operators

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					Shorthand operators
               Shorthand operators

• Shorthand operator:
      • A shorthand operator is a shorter way to express
      something that is already available in the Java
      programming language
      • Shorthand operations do not add any feature to the
      Java programming language
      (So it's not a big deal).
 Shorthand operators +=, -=, *=, /= and *=

• A frequent construct is the following:

      x is a variable in the program

      x = x + value ; // Add value to the variable x
      x = x - value ; // Subtract value to the variable x
      x = x * value ; // Increase the variable x by value times
      and so on...


  Java has a shorthand operator for these kinds of assignment
  statements
    Shorthand operators +=, -=, *=, /= and *=
                    (cont.)
• Operator assignment short hands:

        Operator    Name of the      Example    Equivalent
       symbol       operator                   construct
       +=            Addition        x += 4;   x = x + 4;
                    assignment
       -=            Subtraction     x -= 4;   x = x - 4;
                    assignment
       *=            Multiplicatio   x *= 4;   x = x * 4;
                    n assignment
       /=            Division        x /= 4;   x = x / 4;
                    assignment
       %=            Remainder       x %= 4;   x = x % 4;
                    assignment
 Shorthand operators +=, -=, *=, /= and *=
                 (cont.)
• Exercise: what is printed by the following program
           public class Shorthand1
           {
             public static void main(String[] args)
             {
            int x;

           x = 7;
           x += 4;
           System.out.println(x);

           x = 7;
           x -= 4;
           System.out.println(x);
Shorthand operators +=, -=, *=, /= and *=
                (cont.)

       x = 7;
       x *= 4;
       System.out.println(x);

       x = 7;
       x /= 4;
       System.out.println(x);

        x = 7;
        x %= 4;
        System.out.println(x);
         }
       }
 Shorthand operators +=, -=, *=, /= and *=
                 (cont.)
• Example Program: (Demo above code)
   – Prog file:
     http://mathcs.emory.edu/~cheung/Courses/170/Syllabus/04/Progs/
     Shorthand1.java
• How to run the program:

       • Right click on link and save in a scratch directory
       • To compile: javac Shorthand1.java
       • To run:     java Shorthand1 (You will see the
       answers on the terminal)
    Increment and decrement shorthand
                operators
• Two very commonly used assignment statements are:

               1. x = x + 1;

             and

               2. x = x - 1;

             x is a variable in the program


• Java has shorthand operators to increment and decrement a
  variable by 1 (one).
    Increment and decrement shorthand
             operators (cont.)
• Increment and decrement operators:

        Operator    Name of the    Example    Equivalent
        symbol       operator                 construct

          ++         Increment         x++;   x = x + 1;


           --        Decrement         x--;   x = x - 1;
    Increment and decrement shorthand
             operators (cont.)
• Exercise: what is printed by the following program

             public class Shorthand2
             {
               public static void main(String[] args)
               {
              int x;

              x = 7;
              x++;
              System.out.println(x);

              x = 7;
              x--;
              System.out.println(x);
               }
             }
    Increment and decrement shorthand
             operators (cont.)
• Example Program: (Demo above code)
   – Prog file:
     http://mathcs.emory.edu/~cheung/Courses/170/Syllabus/04/Progs/
     Shorthand2.java
• How to run the program:

       • Right click on link and save in a scratch directory
       • To compile: javac Shorthand2.java
       • To run:     java Shorthand2 (You will see the
       answers on the terminal)

				
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