Operators in C:
An operator is simply a symbol which takes one or more operands or expressions and performs operations.
¾ Operands are variables or expressions which are used in conjunction with operators to evaluate the expression.
¾ If an operator requires one operand, it is called as Unary Operator,
¾ If an operator requires two operands, then it is called as Binary Operator and if it requires three operands, then it is called as ternary operator/conditional operator.
¾ Combination of operands and operators form an expression.
¾ Expressions are sequences of operators, operands, and punctuators that specify a computation.
¾ There are following types of operators to perform different types of operations in C language.
1. Arithmetic Operators
2. Relational Operators
3. Logical Operators
4. Bitwise Operators
5. Ternary or Conditional Operators
6. Assignment Operator
7. Selection Operator
8. Misc Operator
I) Unary Operators
Operator
|
Name
|
Operator
|
Name
|
!
|
Logical NOT
|
++
|
Increment by 1
|
&
|
Address-of
|
–
|
Unary negation
|
( )
|
Cast Operator
|
––
|
Decrement by 1
|
*
|
Pointer dereference
|
~
|
Complement
|
+
|
Unary Plus
|
||
II) Binary Operators
Operator
|
Name
|
Operator
|
Name
|
,
|
Comma
|
/=
|
Division assignment
|
!=
|
Inequality
|
<
|
Less than
|
%
|
Modulus
|
<<
|
Left shift
|
%=
|
Modulus assignment
|
<<=
|
Left shift assignment
|
&
|
Bitwise AND
|
<=
|
Less than or equal to
|
&&
|
Logical AND
|
=
|
Assignment
|
&=
|
Bitwise AND assignment
|
==
|
Equality
|
*
|
Multiplication
|
>
|
Greater than
|
*=
|
Multiplication assignment
|
>=
|
Greater than or equal to
|
+
|
Addition
|
>>
|
Right shift
|
+=
|
Addition assignment
|
>>=
|
Right shift assignment
|
–
|
Subtraction
|
^
|
Exclusive OR
|
–=
|
Subtraction assignment
|
^=
|
Exclusive OR assignment
|
–>
|
Member selection
|
|
|
Bitwise inclusive OR
|
–>*
|
Pointer-to-member selection
|
|=
|
Bitwise inclusive OR assignment
|
/
|
Division
|
||
|
Logical OR
|
All Binary operators are discussed later in this topic only.
1) Arithmetic Operators
There are following arithmetic operators supported by C language. Assume variable ‘A’ holds 10 and variable ‘B’ holds 20 then:
Operator
|
Description
|
Example
|
+
|
Adds two operands
|
A + B will give 30
|
-
|
Subtracts the second operand from the first
|
A - B will give -10
|
*
|
Multiply both operands
|
A * B will give 200
|
/
|
Divide numerator by the denominator
|
B / A will give 2
|
%
|
Modulus Operator and a remainder of after an integer division
|
B % A will give 0
|
++
|
Increment operator, increases integer value by one
|
A++ will give 11
|
--
|
Decrement operator, decreases integer value by one
|
A-- will give 9
|
Program: WAP to demonstrate arithmetic operators.
#include<stdio.h>
#include<conio.h>
void main()
{
int a = 21,b = 10, c;
c = a + b;
printf("Line 1 - Value of c is %d\n", c );
c = a - b;
printf("Line 2 - Value of c is %d\n", c );
c = a * b;
printf("Line 3 - Value of c is %d\n", c );
c = a / b;
printf("Line 4 - Value of c is %d\n", c );
c = a % b;
printf("Line 5 - Value of c is %d\n", c );
c = a++;
printf("Line 6 - Value of c is %d\n", c );
c = a--;
printf("Line 7 - Value of c is %d\n", c );
getch();
}
Output
Line 1 - Value of c is 31
Line 2 - Value of c is 11
Line 3 - Value of c is 210
Line 4 - Value of c is 2
Line 5 - Value of c is 1
Line 6 - Value of c is 21
Line 7 - Value of c is 22
There are two types of Increment / Decrement Operators, first one is pre increment/decrement and the second is post increment/decrement.
i) Pre-Increment:
In pre-increment, the value is first incremented and then used in the expression.
Program: WAP to demonstrate Pre-Increment Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a = 10,b = 2, c;
c = ++a + b; // ++a is pre-increment and now value of a is 11.
printf("Value of c is %d\n", c );
getch();
}
Output
Value of c is 13
ii) Pre-Decrement:
In pre-decrement, the value is first decremented and then used in the expression.
Program : WAP to demonstrate Pre-Decrement Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a = 10,b = 2, c;
c = --a + b; // --a is pre-decrement and now value of a is 9.
printf("Value of c is %d\n", c );
getch();
}
Output
Value of c is 11
iii) Post-Increment:
In post-increment, the expression is executed first and then the value of the variable is incremented.
Program : WAP to demonstrate Post-Increment Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a = 10,b = 2, c;
c = a++ + b; // a++ is post-increment and value of a is 10 (no change).
printf("Value of c is %d\n", c );
printf("Value of a is %d\n", a ); //value of a is 11
getch();
}
Output
Value of c is 12
Value of a is 11
|
iv) Post-Decrement:
In post-decrement, the expression is executed first and then the value of the variable is decremented.
Program : WAP to demonstrate Post-Decrement Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a = 10,b = 2, c;
c = a-- + b; // a-- is post-decrement and value of a is 10 (no change).
printf("Value of c is %d\n", c );
printf("Value of a is %d\n", a ); //value of a is 9
getch();
}
Output
Value of c is 12
Value of a is 9
2) Relational Operators
¾ In C Programming we can compare the value stored between two variables and depending on the result we can follow different blocks using Relational Operator in C.
¾ Relational operators in c programming is used for specifying the relation between two operands such as greater than, less than and equals.
¾ The following table shows all the relational operators supported by C. Assume variable ‘A’ holds 10 and variable ‘B’ holds 20.
Operator
|
Description
|
Example
|
==
|
Checks if the values of two operands are equal or not. If yes, then the condition becomes true.
|
(A == B) is not true.
|
!=
|
Checks if the values of two operands are equal or not. If the values are not equal, then the condition becomes true.
|
(A != B) is true.
|
>
|
Checks if the value of left operand is greater than the value of the right operand. If yes, then the condition becomes true.
|
(A > B) is not true.
|
<
|
Checks if the value of left operand is less than the value of the right operand. If yes, then the condition becomes true.
|
(A < B) is true.
|
>=
|
Checks if the value of left operand is greater than or equal to the value of the right operand. If yes, then the condition becomes true.
|
(A >= B) is not true.
|
<=
|
Checks if the value of left operand is less than or equal to the value of the right operand. If yes, then the condition becomes true.
|
(A <= B)
|
Program: WAP to demonstrate Relational Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a=21,b=10,c;
if(a==b) {
printf(“Line 1 – a is equal to b\n”);
}
else {
printf(“Line 1 – a is not equal to b\n”);
}
if(a < b) {
printf(“Line 2 – a is less than b\n”);
}
else {
printf(“Line 2 – a is not less than b\n”);
}
if(a > b) {
printf(“Line 3 – a is greater than b\n”);
}
else {
printf(“Line 3 – a is not greater than b\n”);
}
if(a <= b) {
printf(“Line 4 – a is less than or equal to b\n”);
}
else {
printf(“Line 4 – a is not less than or equal to b\n”);
}
if(a >= b) {
printf(“Line 5 – a is greater than or equal to b\n”);
}
else {
printf(“Line 5 – a is not greater than or equal to b\n”);
}
getch();
}
Output
Line 1 - a is not equal to b
Line 2 - a is not less than b
Line 3 - a is greater than b
Line 4 - a is not less than or equal to b
Line 5 - a is greater than or equal to b
3) Logical Operators
Following table shows all the logical operators supported by C language. Assume variable A holds 1 and variable B holds 0.
Operator
|
Description
|
Example
|
&&
|
Called Logical AND operator. If both the operands are non-zero, then the condition becomes true.
|
(A && B) is false.
|
||
|
Called Logical OR Operator. If any of the two operands is non-zero, then the condition becomes true.
|
(A || B) is true.
|
!
|
Called Logical NOT Operator. It is used to reverse the logical state of its operand. If a condition is true, then Logical NOT operator will make it false.
|
!(A && B)
|
Program: WAP to demonstrate Logical Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a=5,b=21,c;
clrscr();
if ( a && b ) {
printf("Line 1 - Condition is true\n" );
}
if ( a || b ) {
printf("Line 2 - Condition is true\n" );
}
/* lets change the value of a and b */
a = 0;
b = 10;
if ( a && b ) {
printf("Line 3 - Condition is true\n" );
}
else {
printf("Line 3 - Condition is not true\n" );
}
if ( !(a && b) ) {
printf("Line 4 - Condition is true\n" );
}
getch();
}
Output :
Line 1 - Condition is true
Line 2 - Condition is true
Line 3 - Condition is not true
Line 4 - Condition is true
4) Bitwise Operators
P
|
Q
|
p & q
|
p | q
|
p ^ q
|
0
|
0
|
0
|
0
|
0
|
0
|
1
|
0
|
1
|
1
|
1
|
1
|
1
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
Bitwise operator works on bits and performs bit-by-bit operation. The truth tables for &, |, and ^ is as follows
Assume A = 60 and B = 13 in binary format, they will be as follows −
A = 0011 1100 B = 0000 1101
A&B = 0000 1100 A|B = 0011 1101
A^B = 0011 0001 ~A = 1100 0011
The following table lists the bitwise operators supported by C. Assume variable 'A' holds 60 and variable 'B' holds 13, then
Operator
|
Description
|
Example
|
&
|
Binary AND Operator copies a bit to the result if it exists in both operands.
|
(A & B) = 12, i.e., 0000 1100
|
|
|
Binary OR Operator copies a bit if it exists in either operand.
|
(A | B) = 61, i.e., 0011 1101
|
^
|
Binary XOR Operator copies the bit if it is set in one operand but not both.
|
(A ^ B) = 49, i.e., 0011 0001
|
~
|
Binary Ones Complement Operator is unary and has the effect of 'flipping' bits.
|
(~A ) = -61, i.e,. 1100 0011 in 2's complement form.
|
<<
|
Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.
|
A << 2 = 240 i.e., 1111 0000
|
>>
|
Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.
|
A >> 2 = 15 i.e., 0000 1111
|
Program: WAP to demonstrate Bitwise Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
unsigned int a = 60; /* 60 = 0011 1100 */
unsigned int b = 13; /* 13 = 0000 1101 */
int c = 0;
clrscr();
c = a & b; /* 12 = 0000 1100 */
printf("Line 1 - Value of c is %d\n", c );
c = a | b; /* 61 = 0011 1101 */
printf("Line 2 - Value of c is %d\n", c );
c = a ^ b; /* 49 = 0011 0001 */
printf("Line 3 - Value of c is %d\n", c );
c = ~a; /*-61 = 1100 0011 */
printf("Line 4 - Value of c is %d\n", c );
c = a << 2; /* 240 = 1111 0000 */
printf("Line 5 - Value of c is %d\n", c );
c = a >> 2; /* 15 = 0000 1111 */
printf("Line 6 - Value of c is %d\n", c );
getch();
}
Output
Line 1 - Value of c is 12
Line 2 - Value of c is 61
Line 3 - Value of c is 49
Line 4 - Value of c is -61
Line 5 - Value of c is 240
Line 6 - Value of c is 15
5) Ternary or Conditional Operators
Conditional operators return one value if the condition is true and returns another value is condition is false.
Syntax : (Condition? true_value : false_value);
Example : (A > 100 ? 0 : 1);
In the above example, if A is greater than 100, 0 is returned else 1 is returned. This is equal to if else conditional statements.
Program: WAP to demonstrate Ternary or Conditional Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int x=1, y ;
clrscr();
y = ( (x ==1) ? 2 : 0 ) ;
printf(“x value is %d\n”, x);
printf(“y value is %d”, y);
y = ( (x ==1) ? 2 : 0 ) ;
printf(“x value is %d\n”, x);
printf(“y value is %d”, y);
getch();
}
Output
x value is 1
y value is 2
y value is 2
6) Assignment Operators
In C programs, values for the variables are assigned using assignment operators. For example, if the value “10″ is to be assigned for the variable “sum”, it can be assigned as “sum = 10;” The following table lists the assignment operators supported by the C language.
Operator
|
Description
|
Example
|
=
|
Simple assignment operator. Assigns values from right side operands to left side operand
|
C = A + B will assign the value of A + B to C
|
+=
|
Add AND assignment operator. It adds the right operand to the left operand and assign the result to the left operand.
|
C += A is equivalent to C = C + A
|
-=
|
Subtract AND assignment operator. It subtracts the right operand from the left operand and assigns the result to the left operand.
|
C -= A is equivalent to C = C - A
|
*=
|
Multiply AND assignment operator. It multiplies the right operand with the left operand and assigns the result to the left operand.
|
C *= A is equivalent to C = C * A
|
/=
|
Divide AND assignment operator. It divides the left operand with the right operand and assigns the result to the left operand.
|
C /= A is equivalent to C = C / A
|
%=
|
Modulus AND assignment operator. It takes modulus using two operands and assigns the result to the left operand.
|
C %= A is equivalent to C = C % A
|
<<=
|
Left shift AND assignment operator.
|
C <<= 2 is same as C = C << 2
|
>>=
|
Right shift AND assignment operator.
|
C >>= 2 is same as C = C >> 2
|
&=
|
Bitwise AND assignment operator.
|
C &= 2 is same as C = C & 2
|
^=
|
Bitwise exclusive OR and assignment operator.
|
C ^= 2 is same as C = C ^ 2
|
|=
|
Bitwise inclusive OR and assignment operator.
|
C |= 2 is same as C = C | 2
|
Program: WAP to demonstrate Assignment Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a = 21,c ;
c = a;
printf("Line 1 - = Operator Example, Value of c = %d\n", c );
c += a;
printf("Line 2 - += Operator Example, Value of c = %d\n", c );
c -= a;
printf("Line 3 - -= Operator Example, Value of c = %d\n", c );
c *= a;
printf("Line 4 - *= Operator Example, Value of c = %d\n", c );
c /= a;
printf("Line 5 - /= Operator Example, Value of c = %d\n", c );
c = 200;
c %= a;
printf("Line 6 - %= Operator Example, Value of c = %d\n", c );
c <<= 2;
printf("Line 7 - <<= Operator Example, Value of c = %d\n", c );
c >>= 2;
printf("Line 8 - >>= Operator Example, Value of c = %d\n", c );
c &= 2;
printf("Line 9 - &= Operator Example, Value of c = %d\n", c );
c ^= 2;
printf("Line 10 - ^= Operator Example, Value of c = %d\n", c );
c |= 2;
printf("Line 11 - |= Operator Example, Value of c = %d\n", c );
getch();
}
Output
Line 1 - = Operator Example, Value of c = 21
Line 2 - += Operator Example, Value of c = 42
Line 3 - -= Operator Example, Value of c = 21
Line 4 - *= Operator Example, Value of c = 441
Line 5 - /= Operator Example, Value of c = 21
Line 6 - %= Operator Example, Value of c = 11
Line 7 - <<= Operator Example, Value of c = 44
Line 8 - >>= Operator Example, Value of c = 11
Line 9 - &= Operator Example, Value of c = 2
Line 10 - ^= Operator Example, Value of c = 0
Line 11 - |= Operator Example, Value of c = 2
7) Selection Operator
Theses operators are used to select a certain element of a set of elements. The different operators in this set are listed below:
Operator
|
Description
|
Example
|
[]
|
This operator is used to select an element of an Array
|
int a[20];
|
. |
This is called as period operator and is used to select an element of a structure or union.
|
structurename.struct_variable
|
->
|
This is used to select an element of a structure or union pointed by a pointer.
|
This will be studied later
|
()
|
This is called as a function call operator and used to call or select a function.
|
void main(){
}
|
,
|
The comma(,) operator is used to separate the different values etc.
|
int a,b,c;
|
¾ Braces{}: These opening and ending curly braces marks the start and end of a block of code containing more than one executable statement.
¾ Parentheses(): These special symbols are used to indicate function calls and function parameters.
¾ Brackets[]: Opening and closing brackets are used as array element reference. These indicate single and multidimensional subscripts.
8) Misc Operator
Besides the operators discussed above, there are a few other important operators including sizeof, & and * supported by the C Language.
Operator
|
Description
|
Example
|
sizeof()
|
Returns the size of a variable.
|
sizeof(a), where a is integer, will return 2 byte.
|
&
|
Returns the address of a variable.
|
&a; returns the actual address of the variable.
|
*
|
Pointer to a variable.
|
*a;
|
Program 1.20: WAP to demonstrate Misc. Operator.
#include<stdio.h>
#include<conio.h>
void main()
{
int a = 4;
short b;
double c;
int* ptr;
/* example of sizeof operator */
printf("Line 1 - Size of variable a = %d\n", sizeof(a) );
printf("Line 2 - Size of variable b = %d\n", sizeof(b) );
printf("Line 3 - Size of variable c= %d\n", sizeof(c) );
/* example of & and * operators */
ptr = &a; /* 'ptr' now contains the address of 'a'*/
printf("value of a is %d\n", a);
printf("*ptr is %d.\n", *ptr);
getch();
}
Output
Line 1 - Size of variable a = 2
Line 2 - Size of variable b = 2
Line 3 - Size of variable c= 8
value of a is 4
*ptr is 4.
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