unary operators

Unary Arithmetic Operators

These operators require only one operand to perform operation .it can again divided into Two categories

They are

1.      Unary minus Operator

2.      Increment/ Decrement operators

Unary minus or negation operator

This operator can be used to negate the value of a variable i.e it converts positive value into negative and vice versa.

For example

int   a= 10;   ------->        Line 1          

int  b= -a;    -------->        Line 2

In the above Example Line 1 a will be stored with the value 10(Positive value), and in Line 2   int b= -a the value of a(10) is converted into negative  i.e -10 and stored into the variable b.

Note: Minus operator can be used in both unary and binary operations.

Increment /Decrement operators

These unary operators are used to increase or decrease the value of variable by 1.increment operators are represented by ++ and decrement operators are represented by --.These operators can be used in two ways

1.      Pre-fix operator

2.      Post-fix operator

Pre-fix operator: If the operator is used before the variable name then the operator is known as prefix operator

For Example    

++a ;

--a ;

In the above example ++ and --are prefixes to the variable a. hence ++ is known as pre-increment and - - is known as pre - decrement.

Post-fix operator: If the operator is used after the variable name then the operator is known as post-fix operator

For Example    

a++;

a--;

In the above example ++ and --are post-fixes to the variable a. Hence ++ is known as post-increment and - - is known as post - decrement.

Pre-Increment Operator:

Here   first it increases the value of the variable by 1.and then the new value in the variable will be used in the expression

For example

Int   a =10;

Int b;

 b=++a; then a=? and b= ?

in the above example value of a is incremented by 1 first i.e a becomes 11 and then the value of a(11) will be assigned to b . There fore

a=11

b=11

Pre-decrement Operator:

Here   first it decreases the value of the variable by 1.and then the new value in the variable will be used  in the expression

For example

Int  a =10;

Int b;

 b=--a;  then a= ? and b= ?

in the above example value of a is incremented by 1 first i.e a becomes 11 and then the value of a(11) will be assigned to b . There fore

a=9

b=9

Post Increment operator

post  Increment operator: if the operator is post increment  operator then the value of variable is used in the expression first and then the value of the variable increments next.

For example:

Int a=10;

Int b;

b=a++;

Here ++ is post-increment operator, since the value of the variable a(10) is assigned to b is first and then value of a is incremented by 1 .i.e. a becomes 11.There fore

a=11;

b=10;

Post decrement operator: if the operator is post decrement operator then the value of variable is used in the expression first and then the value of the variable increments next.

For example:

Int a=10;

Int b;

b=a--;

Here -- is post-increment operator, since the value of the variable a (10) is assigned to b is first and then value of a is decremented by 1 .i.e. a becomes 9.There fore

a=9;

b=10;