Operators and Reference variable in C++

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Topics
Various operators
ׅArithmetic Operators
Relational Operators
Logical Operators
Assignment Operators
Increment and Decrement Operators
Conditional Operator
Special Operators
Extraction operator ( >>)
Insertion operator (<<)
Scope resolution operator (::)
member dereferencing operators

Reference variable

Various operators used in C++.

An operator is a symbol that tells the compiler to perform certain mathematical or logical operation.

1. Arithmetic Operators

Arithmetic operators are used for mathematical calculation. C++ support following arithmetic operators

+	Addition or unary plus
-	Subtraction or unary minus
*	Multiplication
/	Division
%	Modulo division

2. Relational Operators

Relational operators are used to comparing two numbers and taking decisions based on their relation.
Relational expressions are used in decision statements such as if, for, while, etc...

< less than
<= less than or equal to
> greater than
>= greater than or equal to
== is equal to
!= is not equal to

3. Logical Operators

Logical operators are used to testing more than one condition and make decisions

&& logical AND (Both non zero then true, either is zero then false)
|| logical OR (Both zero then false, either is non zero then true)
! logical NOT (non zero then false, zero then true)

4. Assignment Operators

Assignment operators are used to assigning the result Of an expression to a variable. C++ also supports shorthand assignment operators which simplify operation with the assignment.

= Assigns value Of right side to left side
+= a+=1 is same as a = a + 1
-= a-= 1 is same as a = a -1
*= a *=1 is same as a = a*1
/= a /=1 is same as a = a/ 1
%= a %= 1 is same as a = a % 1

5. Increment and Decrement Operators

These are special operators in C++ which are generally not found in other languages.

+ + Increments value by 1.
a++ is postfix, the expression is evaluated first and then the value is incremented.
Ex. a=10; b=a++; after this statement, 11, b = 10.
++a is prefix, the value is incremented first and then the expression is evaluated.
Ex. a=10; b=++a; after this statement, 11, b = 11.

-- Decrements value by 1.
a-- is postfix, the expression is evaluated first and then the value is decremented.
Ex. a=10; b=a--; after this statement, 9, b = 10.
--a is the prefix, the value is decremented first and then the expression is evaluated.
Ex. a=10; b=--a; after this statement, 9, b = 9.

6. Conditional Operator

A ternary operator is known as Conditional Operator.
expl?exp2:exp3 if expl is true then execute exp2 otherwise exp3

Ex: x=(a>b)?a:b; which is same as

if (a>b)

x=a;

else

x=b;

7. Special Operators

& Address operator, it is used for determining address Of the variable.
* Pointer operator, it is used to declare pointer variable and to get value from it.
, Comma operator. It is used to link the related expressions together.
sizeof It returns the number Of bytes the operand occupies.
. member selection operator, used in the structure.
-> member selection operator, used in the pointer to structure.

9. Extraction operator ( >>)

Extraction operator (>>) is used with cin to input data from the keyboard.

10. Insertion operator (<<)

Insertion operator (<<) is used with cout to output data from the keyboard.

11. Scope resolution operator (::)

Scope resolution operator (: : ) is used to define the already declared member functions Of the class.
The scope resolution operator is used to resolve or extend the scope Of variable.
C++ is block structured language. We know that the same variable name can be used to have a different meaning in the different block.
The scope resolution operator will refer value Of global variable from anywhere (also from inner block).
Without scope resolution operator all variable will refer local value.

12. What is reference variable?

• A reference variable provides an alias (alternate name) for a previously defined variable.

• This mechanism is used in object-oriented programming because it permits the manipulation Of objects by reference, and eliminates the copying Of object parameters back and forth.

• It is also important to note that references can be created not only for built-in data types but also for the user-defined data types.
• reference variable store the address of another variable .

• Syntax: Data_type & reference_name = variable_name

• For example :

int a=100;

int &b=a;//Now both a and b will give the same value.

8) member dereferencing operators.