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Siva Nookala - 17 Feb 2019

## About Increment And Decrement Operators In Java :

Increment Operator increases its operand by 1. The Decrement Operator decreases its operand by 1. Instead of `x = x + 1;` we could do `x++;`

Increment And Decrement Operators can be used both postfix (`x++`) and prefix (`++x`). In the postfix form it is used and then incremented, where as in prefix form it is incremented and then used.
`int x = 42;int y = ++x; // same as x = x + 1; followed by int y = x;System.out.println("x = " + x + " y = " + y);`
The above code prints x = 43 y = 43 where as the below code prints x = 43 y = 42
`int x = 42;int y = x++; // same as int y = x; followed by x = x + 1;System.out.println("x = " + x + " y = " + y);`
Pre and Post Increment
`class PreAndPostIncrement{    public static void main(String arg[])    {        int a = 5;        int b = 2;        int c;        int d;        c = ++b; // LINE A        d = a++; // LINE B        c++; // LINE C        System.out.println("a = " + a + " b = " + b + " c = " + c + " d = " + d);        }}`
OUTPUT

a = 6 b = 3 c = 4 d = 5

DESCRIPTION

Here `a` and `b` are declared as integers and they are assigned to `5` and `2` respectively.
In `LINE A`, we have prefix increment operator i.e. `++` before the operand `b` i.e. ( `++b` ). So the value of `b` is first incremented from `2` to `3` and then assigned to `c`. Hence `c` becomes `3`.
In `LINE B`, where we have postfix increment operator i.e. `++` after the operand `a` i.e. ( `a++` ), the value of `a` is first assigned to `d`, so `d` becomes `5`. Later `a` is incremented from `5` to `6`.
In `LINE C`, `c` is incremented, so it goes from `3` to `4`. Here there is no difference whether we use postfix ( `c++` ) or prefix ( `++c` ) increment since we are not assigning it or using it as part of some other expression.

THINGS TO TRY
• Change `LINE A` to `c = b++;` and LINE B to `d = ++a;` and see what will be the output.
• Use decrement operator `--` instead of increment operator by changing `LINE A` to `c = --b;` and `LINE B` to `d = --a;` and validate the output. The decrement operator decreases the value of operand by `1`. If it was `4`, it will become `3`.

2-min video about Increment and Decrement operators

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