Tuesday, 2 July 2013

PROGRAMMING PART OF C# : WHAT ARE OPERATORS IN THIS LANGUAGE AND WHY DO WE NEED IT?

WHAT ARE OPERATORS AND WHY DO WE NEED IT?

Operators are used to compute results and compare the data values of a program.  A program often involves decision-making and iterative tasks (repetitive tasks).  You can use conditional constructs for decision-making and conditional constructs for repetitive for decision making and repetitive tasks in your programs.
This post discusses the various types of operators used in the C# language.  In addition, the chapter discusses the various conditional and looping (repetition) constructs supported by C#.
Using Operators
Consider an example, where you need to develop a C# program for displaying the result and rank of the students in a class.  To compute result and ranks, the application needs to perform some calculations and comparisons.  You can use various operators in your C# program and use them to compute the results and ranks of the students.
Operators like + (addition) and –(subtraction) are used to process variables and return a value.  An operator is a set of one or more characters that is used for computations or comparisons.  Operators can change one or more data values, called operands, into a new data value.
Consider the following example:
X+Y
            Operator
    X   +    Y
    
             
 
The preceding expression uses two operands, x and y, and an operator, +, to add the values of both the variables.  The following figure shows the operator and operands used in the preceding expression.
 








You can use the following types of operators in your C# programs:
·         Arithmetic operators
·         Arithmetic  assignment operators
·         Unary operators
·         Comparison Operators
·         Logical Operators
ARITHMETIC OPERATORS
Arithmetic operators are used to perform arithmetic operations on variables.  The following table describes the commonly used arithmetic operators.
OPERATOR
DESCRIPTION
EXAMPLE
+
USED TO ADD TWO NUMBERS
X=Y+Z
-
USED TO SUBTRACT TWO NUMBERS
X=Y-Z
*
USED TO MULTIPLY TWO NUMBERS
X=Y*Z
/
USED TO DIVIDE ONE NUMBER BY ANOTHER
X=Y/Z
%
USED TO DIVEIDE TWO NUMBERS AND RETURN THE REMAINDER.  THE OPERATOR IS CALLED AS MODULUS OPERATOR
X=Y%Z


ARITHMETIC ASSIGNMENT OPERATORS
Arithmetic assignment operators are used to perform arithmetic operations on two given operands and to assign the resultant value to any one of them
The following table lists the usage and describes the commonly used arithmetic assignment operators.
OPERATOR
USAGE
DESCRIPTION
=
X=5;
Store the value x in 5
+=
X+=5;
Same as X=X+5
-=
X-=5;
Same as X=X-5
*=
X*=5;
Same as X=X*5
/=
X/=5;
Same as X=X/5
%=
X%=Y;
Same as X=X%5
UNARY OPERATORS
Unary operators are used to increment or decrement the value of an operand by 1.  The following table explains the usage of the increment and decrement operators.
OPERATOR
USAGE
DESCRIPTION
EXAMPLE
++
++Operand;
(pre increment operator) or, operand++;
(post increment)
Used to increment the value of an operand by 1
Y=++X;
If the initial value of X is 5, after the preceding statement, values of both X and Y will be 6.  This is because it will first increment the value of x by 1 and then assign it to Y.
Y=X++;
If the initial value of x is 5, after the execution of the preceding   statement, value of x will be 6 and the value of y will be 5.  This is because it will first assign the value of x to y and then increment the value of X by 1.
--
--Operand;
(Pre decrement operator)
Or,
Operand--;
(Post decrement operator)
Used to decrement the value of an operand by 1
Y=--X;
If the initial value of x is 5, after the execution of the preceding statement, values of X and Y will be 4.  This is because it will first decrement the value of X by 1 and then assign the value to Y.
Y=X--;
 If the initial value of X is 5, after the execution of the preceding statement, value of X will be 4, and the value of Y will be 5.  This is because it will first assign the value of X to Y and then decrement the value of X by 1.
LOGICAL OPERATORS
Logical operators are used to evaluate expressions and return a Boolean value.  The following table explains the usage of logical operators.
OPERATOR
USAGE
DESCRIPTION
EXAMPLE
&&
Expression1  && Expression2
Returns true if both expression1 and expression2 are true
Bool result;
String str1, str2;
str1 =”Korea”;
str2=”France”;
Result= (str1=”Korea”) && (str2=”France”);
Console.WriteLine(result.ToString());
The preceding code snippet will print “True” on the screen because str1 has the value “Korea” and str2 has the value “France”

!
! Expression
Returns true if the expression is false.
Bool result;
Int x;
X=20;
Result=(! (x==10)) && (str2=”France”);
Console.WriteLine(result.ToString());
The preceding code snippet will print “True” on the screen because str1 has the value “(x==10)”

||
Expression1
||
Expression2
Returns true if either of  expression1 and expression2 are true or both of them are true
Bool result;
String str1, str2;
str1 =”Korea”;
str2=”France”;
Result= (str1=”Korea”) ||(str2=”France”);
Console.WriteLine(result.ToString());
The preceding code snippet will print “True” on the screen because str1 has the value “Korea” or str2 has the value “France”

^
Expression1
^
Expression2
Returns true if either of  expression1 and expression2 are true
It returns false if both expression1 and expression2 are true or if both expression1 and expression2 are false
Bool result;
String str1, str2;
str1 =”Korea”;
str2=”France”;
Result= (str1=”Korea”) ^(str2=”France”);
Console.WriteLine(result.ToString());
This will print “False” on the screen because both the expression are “True”



COMPARISION OPERATOR
Comparison operators are used to compare two values and perform an action on the basis of the result of that comparison.  Whenever you use comparison operator, the expression result in a Boolean value, ‘true’ or ‘false’.  The following table explains the usage of some commonly used comparison operators.
Operator
Usage
Description
Example
(In the following examples, the value of X is assumed to be 20 and the value of Y is assumed to be 25)
< 
Expression1
< 
Expression2
Used to check whether Expression1 is less than Expression2
Bool Result;
Result = X<Y;
Result will have the value true
> 
Expression1
> 
Expression2
Used to check whether Expression1 is more than Expression2
Bool Result;
Result = X>Y;
Result will have the value false
<=
Expression1
<=
Expression2
Used to check whether Expression1 is less than or equal to Expression2
Bool Result;
Result = X<=Y;
Result will have the value true
=>
Expression1
<=
Expression2
Used to check whether Expression1 is greater than or equal to Expression2
Bool Result;
Result = X=>Y;
Result will have the value false
==
Expression1
==
Expression2
Used to check whether Expression1 is  equal to Expression2
Bool Result;
Result = X==Y;
Result will have the value false
=!
Expression1
!=
Expression2
Used to check whether Expression1 is  not equal to Expression2
Bool Result;
Result = X!=Y;
Result will have the value true