by Dinesh Thakur

An operator is a symbol which helps the user to command the computer to do a certain mathematical or logical manipulations. Operators are used in C language program to operate on data and variables. C has a rich set of operators which can be classified as

(1) Arithmetic Operators

(2) Relational Operators

(3) Logical Operators

(4) Assignment Operators

(5) Increments and Decrement Operators

(6) Conditional Operators

(7) Bitwise Operators

(8) Special Operators

(1) Arithmetic Operators : All the basic arithmetic operations can be carried out in C. All the operators have almost the same meaning as in other languages. Both unary and binary operations are available in C language. Unary operations operate on a singe operand, therefore the number 5 when operated by unary – will have the value –5.

Examples of arithmetic operators are :

*x + y*

*x - y*

*-x + y*

*a * b + c*

*-a * b*

*etc.,*

here a, b, c, x, y are known as operands. The modulus operator is a special operator in C language which evaluates the remainder of the operands after division.

**Example :**

*.*

*#include //include header file stdio.h*

*void main() //tell the compiler the start of the program*

*{*

*int numb1, num2, sum, sub, mul, div, mod; //declaration of variables*

*scanf (“%d %d”, &num1, &num2); //inputs the operands*

*sum = num1+num2; //addition of numbers and storing in sum.*

*printf(“\n Thu sum is = %d”, sum); //display the output*

*sub = num1-num2; //subtraction of numbers and storing in sub.*

*printf(“\n Thu difference is = %d”, sub); //display the output*

*mul = num1*num2; //multiplication of numbers and storing in mul.*

*printf(“\n Thu product is = %d”, mul); //display the output*

*div = num1/num2; //division of numbers and storing in div.*

*printf(“\n Thu division is = %d”, div); //display the output*

*mod = num1%num2; //modulus of numbers and storing in mod.*

*printf(“\n Thu modulus is = %d”, mod); //display the output*

*}*

*.*

**Integer Arithmetic : **When an arithmetic operation is performed on two whole numbers or integers than such an operation is called as integer arithmetic. It always gives an integer as the result. Let x = 27 and y = 5 be 2 integer numbers.

Then the integer operation leads to the following results :

*x + y = 32*

*x – y = 22*

*x * y = 115*

*x % y = 2*

*x / y = 5*

In integer division the fractional part is truncated.

**Floating Point Arithmetic : **When an arithmetic operation is preformed on two real numbers or fraction numbers such an operation is called floating point arithmetic. The floating point results can be truncated according to the properties requirement. The remainder operator is not applicable for floating point arithmetic operands.

*Let x = 14.0 and y = 4.0 then*

*x + y = 18.0*

*x – y = 10.0*

*x * y = 56.0*

*x / y = 3.50*

**Mixed mode arithmetic : **When one of the operand is real and other is an integer and if the arithmetic operation is carried out on these 2 operands then it is called as mixed mode arithmetic. If any one operand is of real type then the result will always be real thus 15/10.0 = 1.5.

**(2) Relational Operators : **Often it is required to compare the relationship between operands and bring out a decision and program accordingly. This is when the relational operator come into picture. C supports the following relational operators.

It is required to compare the marks of 2 students, salary of 2 persons, we can ompare them using relational operators. A simple relational expression contains only one relational operator and takes the following form :

**exp1 relational operator exp2**

Where exp1 and exp2 are expressions, which may be simple constants, variables or combination of them. Given below is a list of examples of relational expressions and evaluated values.

*6.5 <= 25 TRUE*

*-65 > 0 FALSE*

*10 < 7 + 5 TRUE*

* *

Relational expressions are used in decision making statements of C language such as if, while and for statements to decide the course of action of a running program

(3) Logical Operators : C has the following logical operators, they compare or evaluate logical and relational expressions.

** **

**Logical AND (&&) : **This operator is used to evaluate 2 conditions or expressions with relational operators simultaneously. If both the expressions to the left and to the right of the logical operator is true then the whole compound expression is true.

**Example :**

* *

*a > b && x = = 10*

The expression to the left is a > b and that on the right is x == 10 the whole expression is true only if both expressions are true i.e., if a is greater than b and x is equal to 10.

**Logical OR (||) : **The logical OR is used to combine 2 expressions or the condition evaluates to true if any one of the 2 expressions is true.

** **

**Example :**

* *

*a < m || a < n*

The expression evaluates to true if any one of them is true or if both of them are true. It evaluates to true if a is less than either m or n and when a

is less than both m and n.

**Logical NOT (!) : **The logical not operator takes single expression and evaluates to true if the expression is false and evaluates to false if the expression is true. In other words it just reverses the value of the expression.

** **

**For example :**

*! (x >= y)*

The NOT expression evaluates to true only if the value of x is neither greater than or equal to y.

**(4) Assignment Operators : **The Assignment Operator evaluates an expression on the right of the expression and substitutes it to the value or variable on the left of the expression.

**Example :**

* *

*x = a + b*

Here the value of a+b is evaluated and substituted to the variable x. In addition, C has a set of shorthand assignment operators of the form.

var oper = exp;

Here var is a variable, exp is an expression and oper is a C binary arithmetic operator. The operator oper = is known as shorthand assignment operator.

** **

**Example :**

* *

*x + = 1 is same as x = x + 1*

The commonly used shorthand assignment operators are as follows:

Example for using shorthand assignment operator :

*#define N 100 //creates a variable N with constant value 100*

*#define A 2 //creates a variable A with constant value 2*

* *

*main() //start of the program*

*{*

*int a; //variable a declaration*

*a = A; //assigns value 2 to a*

*while (a < N) //while value of a is less than N*

*{ //evaluate or do the following*

*printf(“%d \n”,a); //print the current value of a*

*a *= a; //shorthand form of a = a * a*

*} //end of the loop*

*} //end of the program*

*.*

Using ifs to decide on a discount

* *

*#include <stdio.h>*

* *

*void **main() {*

*const double **price = 3.50; /* price*/*

*int **quantity = 0;*

*printf("Enter the number that you want to buy:"); /* Prompt message */*

*scanf(" %d", &quantity); /* Read the input */*

*/* Test for order quantity qualifying for a discount */*

*if**( quantity>20) /* 5% discount */*

*printf("The price for %d is $%.2f\n", quantity, quantity * price * 0.95);*

*else*

*/* No discount */*

*printf("The price for %d is $%.2f\n", quantity, quantity * price); }*

* *

*include <stdio.h>*

* *

*void **main()*

*{*

*int **number = 0;*

*printf("\nEnter an integer between 1 and 10: ");*

*scanf("%d",&number);*

*if **(number > 7)*

*printf("You entered %d which is greater than 7\n", number);*

*if **(number < 3)*

*printf("You entered %d which is less than 3\n", number);*

*}*

Dinesh Thakur is a Technology Columinist and founder of Computer Notes and Technology Motivation.
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