OPERATORS
An operator is a symbol that tells the compiler to perform specific mathematical or logical functions. C language is rich in built-in operators and provides the following types of operators:
 |
| operators |
Relational Operators
Logical Operators
Bitwise Operators
Assignment Operators
Misc Operators
We will, in this chapter, look into the way each operator works.
Arithmetic Operators in C
The following table shows all the arithmetic operators supported by the C language. Assume variable A holds 10 and variable B holds 20, then:
 |
| Arithmetic operators |
Example Try the following example to understand all the arithmetic operators in C:
#include <stdio.h>
main()
{
int a = 21;
int b = 10;
int 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 );
}
When you compile and execute the above program, it produces the following result:
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
Relational Operators
The following table shows all the relational operators in C. Assume variable A holds 10 and variable B holds 20, then:
 |
| relational operators |
Example Try the following example to understand all the relational operators in C:
#include <stdio.h>
main()
{
int a = 21;
int b = 10;
int 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" );
}
/* Lets change value of a and b */
a = 5;
b = 20;
if ( a <= b )
{
printf("Line 4 - a is either less than or equal to b\n" );
}
if ( b >= a )
{
printf("Line 5 - b is either greater than or equal to b\n" );
}
}
When you compile and execute the above program, it produces the following result:
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 either less than or equal to b
Line 5 - b is either greater than or equal to b
Logical Operators
Following table shows all the logical operators in C language. Assume variable A holds 1 and variable B holds 0, then:
 |
| logical operators |
Example Try the following example to understand all the logical operators in C:
#include <stdio.h>
main()
{
int a = 5;
int b = 20;
int c ;
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" );
}
}
When you compile and execute the above program, it produces the following result:
Line 1 - Condition is true
Line 2 - Condition is true
Line 3 - Condition is not true
Line 4 - Condition is true
Bitwise Operators
Bitwise operators work on bits and perform bit-by-bit operation. The truth table for &, |, and ^ is as follows:
 |
| bitwise operators |
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 in C. Assume variable ‘A’ holds 60 and variable ‘B’ holds 13, then:
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Example Try the following example to understand all the bitwise operators in C:
#include <stdio.h>
main()
{
unsigned int a = 60; /* 60 = 0011 1100 */
unsigned int b = 13; /* 13 = 0000 1101 */
int c = 0;
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 );
}
When you compile and execute the above program, it produces the following result:
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
Assignment Operators
The following tables lists the assignment operators in C language:
 |
| assignment operators |
Example Try the following example to understand all the assignment operators in C:
#include <stdio.h>
main()
{
int a = 21;
int 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 );
}
When you compile and execute the above program, it produces the following result:
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
Misc Operators ↦ sizeof & ternary
Besides the operators discussed above, there are a few other important operators including sizeof and ? : supported by the C Language.
 |
| Misc Operators or sizeof & ternary |
Example Try following example to understand all the miscellaneous operators in C:
#include <stdio.h>
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);
/* example of ternary operator */
a = 10;
b = (a == 1) ? 20: 30;
printf( "Value of b is %d\n", b );
b = (a == 10) ? 20: 30;
printf( "Value of b is %d\n", b );
}
When you compile and execute the above program, it produces the following result:
value of a is 4
*ptr is 4.
Value of b is 30
Value of b is 20
Operators Precedence in C
Operator precedence determines the grouping of terms in an expression and decides how an expression is evaluated. Certain operators have higher precedence than others; for example, the multiplication operator has a higher precedence than the addition operator.
For example, x = 7 + 3 * 2; here, x is assigned 13, not 20 because operator * has a higher precedence than +, so it first gets multiplied with 3*2 and then adds into 7.
Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Within an expression, higher precedence operators will be evaluated first.
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| Operators Precedence in C |
Example Try the following example to understand operator precedence in C:
#include <stdio.h>
main()
{
int a = 20;
int b = 10;
int c = 15;
int d = 5;
int e;
e = (a + b) * c / d; // ( 30 * 15 ) / 5
printf("Value of (a + b) * c / d is : %d\n", e );
e = ((a + b) * c) / d; // (30 * 15 ) / 5
printf("Value of ((a + b) * c) / d is : %d\n" , e );
e = (a + b) * (c / d); // (30) * (15/5)
printf("Value of (a + b) * (c / d) is : %d\n", e );
e = a + (b * c) / d; // 20 + (150/5)
printf("Value of a + (b * c) / d is : %d\n" , e );
return 0;
}
When you compile and execute the above program, it produces the following result:
Value of (a + b) * c / d is : 90
Value of ((a + b) * c) / d is : 90
Value of (a + b) * (c / d) is : 90
Value of a + (b * c) / d is : 50
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