C Operators

C Programming Operators

C programming has various operators to perform tasks including arithmetic, conditional and bitwise operations. You will learn about various C operators and how to use them in this tutorial.
Operators in C programming
An operator is a symbol which operates on a value or a variable. For example: + is an operator to perform addition.
C programming has wide range of operators to perform various operations. For better understanding of operators, these operators can be classified as:
Operators in C programming
Arithmetic Operators
Increment and Decrement Operators
Assignment Operators
Relational Operators
Logical Operators
Conditional Operators
Bitwise Operators
Special Operators

C Arithmetic Operators

An arithmetic operator performs mathematical operations such as addition, subtraction and multiplication on numerical values (constants and variables).
OperatorMeaning of Operator
+addition or unary plus
-subtraction or unary minus
*multiplication
/division
%remainder after division( modulo division)

Example #1: Arithmetic Operators

// C Program to demonstrate the working of arithmetic operators
#include <stdio.h>
int main()
{
    int a = 9,b = 4, c;
    
    c = a+b;
    printf("a+b = %d \n",c);

    c = a-b;
    printf("a-b = %d \n",c);
    
    c = a*b;
    printf("a*b = %d \n",c);
    
    c=a/b;
    printf("a/b = %d \n",c);
    
    c=a%b;
    printf("Remainder when a divided by b = %d \n",c);
    
    return 0;
}
Output
a+b = 13
a-b = 5
a*b = 36
a/b = 2
Remainder when a divided by b=1
The operators +, - and * computes addition, subtraction and multiplication respectively as you might have expected.
In normal calculation, 9/4 = 2.25. However, the output is 2 in the program.
It is because both variables a and b are integers. Hence, the output is also an integer. The compiler neglects the term after decimal point and shows answer 2 instead of 2.25.
The modulo operator % computes the remainder. When a = 9 is divided by b = 4, the remainder is 1. The % operator can only be used with integers.
Suppose a = 5.0, b = 2.0, c = 5 and d = 2. Then in C programming,

a/b = 2.5  // Because both operands are floating-point variables
a/d = 2.5  // Because one operand is floating-point variable
c/b = 2.5  // Because one operand is floating-point variable
c/d = 2     // Because both operands are integers

Increment and decrement operators

C programming has two operators increment ++ and decrement -- to change the value of an operand (constant or variable) by 1.
Increment ++ increases the value by 1 whereas decrement -- decreases the value by 1. These two operators are unary operators, meaning they only operate on a single operand.

Example #2: Increment and Decrement Operators

// C Program to demonstrate the working of increment and decrement operators
#include <stdio.h>
int main()
{
    int a = 10, b = 100;
    float c = 10.5, d = 100.5;

    printf("++a = %d \n", ++a);

    printf("--b = %d \n", --b);

    printf("++c = %f \n", ++c);

    printf("--d = %f \n", --d);

    return 0;
}
Output
++a = 11
--b = 99
++c = 11.500000
++d = 99.500000
Here, the operators ++ and -- are used as prefix. These two operators can also be used as postfix like a++ and a--. 

C Assignment Operators

An assignment operator is used for assigning a value to a variable. The most common assignment operator is =
OperatorExampleSame as
=a = ba = b
+=a += ba = a+b
-=a -= ba = a-b
*=a *= ba = a*b
/=a /= ba = a/b
%=a %= ba = a%b

Example #3: Assignment Operators

// C Program to demonstrate the working of assignment operators
#include <stdio.h>
int main()
{
    int a = 5, c;

    c = a;
    printf("c = %d \n", c);

    c += a; // c = c+a
    printf("c = %d \n", c);

    c -= a; // c = c-a
    printf("c = %d \n", c);

    c *= a; // c = c*a
    printf("c = %d \n", c);

    c /= a; // c = c/a
    printf("c = %d \n", c);

    c %= a; // c = c%a
    printf("c = %d \n", c);

    return 0;
}
Output
c = 5 
c = 10 
c = 5 
c = 25 
c = 5 
c = 0

C Relational Operators

A relational operator checks the relationship between two operands. If the relation is true, it returns 1; if the relation is false, it returns value 0.
Relational operators are used in decision making and loops.
OperatorMeaning of OperatorExample
==Equal to5 == 3 returns 0
>Greater than5 > 3 returns 1
<Less than5 < 3 returns 0
!=Not equal to5 != 3 returns 1
>=Greater than or equal to5 >= 3 returns 1
<=Less than or equal to5 <= 3 return 0

Example #4: Relational Operators

// C Program to demonstrate the working of arithmetic operators
#include <stdio.h>
int main()
{
    int a = 5, b = 5, c = 10;

    printf("%d == %d = %d \n", a, b, a == b); // true
    printf("%d == %d = %d \n", a, c, a == c); // false

    printf("%d > %d = %d \n", a, b, a > b); //false
    printf("%d > %d = %d \n", a, c, a > c); //false


    printf("%d < %d = %d \n", a, b, a < b); //false
    printf("%d < %d = %d \n", a, c, a < c); //true


    printf("%d != %d = %d \n", a, b, a != b); //false
    printf("%d != %d = %d \n", a, c, a != c); //true


    printf("%d >= %d = %d \n", a, b, a >= b); //true
    printf("%d >= %d = %d \n", a, c, a >= c); //false


    printf("%d <= %d = %d \n", a, b, a <= b); //true
    printf("%d <= %d = %d \n", a, c, a <= c); //true

    return 0;

}
Output
5 == 5 = 1
5 == 10 = 0
5 > 5 = 0
5 > 10 = 0
5 < 5 = 0
5 < 10 = 1
5 != 5 = 0
5 != 10 = 1
5 >= 5 = 1
5 >= 10 = 0
5 <= 5 = 1
5 <= 10 = 1

C Logical Operators

An expression containing logical operator returns either 0 or 1 depending upon whether expression results true or false. Logical operators are commonly used in decision making in C programming.
OperatorMeaning of OperatorExample
&&Logial AND. True only if all operands are true If c = 5 and d = 2 then, expression ((c == 5) && (d > 5)) equals to 0.
||Logical OR. True only if either one operand is trueIf c = 5 and d = 2 then, expression ((c == 5) || (d > 5)) equals to 1.
!Logical NOT. True only if the operand is 0If c = 5 then, expression ! (c == 5) equals to 0.

Example #5: Logical Operators

// C Program to demonstrate the working of logical operators

#include <stdio.h>
int main()
{
    int a = 5, b = 5, c = 10, result;

    result = (a == b) && (c > b);
    printf("(a == b) && (c > b) equals to %d \n", result);

    result = (a == b) && (c < b);
    printf("(a == b) && (c < b) equals to %d \n", result);

    result = (a == b) || (c < b);
    printf("(a == b) || (c < b) equals to %d \n", result);

    result = (a != b) || (c < b);
    printf("(a != b) || (c < b) equals to %d \n", result);

    result = !(a != b);
    printf("!(a == b) equals to %d \n", result);

    result = !(a == b);
    printf("!(a == b) equals to %d \n", result);

    return 0;
}
Output
(a == b) && (c > b) equals to 1 
(a == b) && (c < b) equals to 0 
(a == b) || (c < b) equals to 1 
(a != b) || (c < b) equals to 0 
!(a != b) equals to 1 
!(a == b) equals to 0
Explanation of logical operator program
  • (a == b) && (c > 5) evaluates to 1 because both operands (a == b) and (c > b) is 1 (true).
  • (a == b) && (c < b) evaluates to 0 because operand (c < b) is 0 (false).
  • (a == b) || (c < b) evaluates to 1 because (a = b) is 1 (true).
  • (a != b) || (c < b) evaluates to 0 because both operand (a != b) and (c < b) are 0 (false).
  • !(a != b) evaluates to 1 because operand (a != b) is 0 (false). Hence, !(a != b) is 1 (true).
  • !(a == b) evaluates to 0 because (a == b) is 1 (true). Hence, !(a == b) is 0 (false).

Bitwise Operators

During computation, mathematical operations like: addition, subtraction, addition and division are converted to bit-level which makes processing faster and saves power.
Bitwise operators are used in C programming to perform bit-level operations.
OperatorsMeaning of operators
&Bitwise AND
|Bitwise OR
^Bitwise exclusive OR
~Bitwise complement
<<Shift left
>>Shift right
Visit bitwise operator in C to learn more.

Other Operators

Comma Operator

Comma operators are used to link related expressions together. For example:
int a, c = 5, d;

The sizeof operator

The sizeof is an unary operator which returns the size of data (constant, variables, array, structure etc).

Example #6: sizeof Operator

#include <stdio.h>
int main()
{
    int a, e[10];
    float b;
    double c;
    char d;
    printf("Size of int=%lu bytes\n",sizeof(a));
    printf("Size of float=%lu bytes\n",sizeof(b));
    printf("Size of double=%lu bytes\n",sizeof(c));
    printf("Size of char=%lu byte\n",sizeof(d));
    printf("Size of integer type array having 10 elements = %lu bytes\n", sizeof(e));
    return 0;
}
Output
Size of int = 4 bytes
Size of float = 4 bytes
Size of double = 8 bytes
Size of char = 1 byte
Size of integer type array having 10 elements = 40 bytes

 C Ternary Operator (?:)

A conditional operator is a ternary operator, that is, it works on 3 operands.

Conditional Operator Syntax

conditionalExpression ? expression1 : expression2
The conditional operator works as follows:
  • The first expression conditionalExpression is evaluated first. This expression evaluates to 1 if it's true and evaluates to 0 if it's false.
  • If conditionalExpression is true, expression1 is evaluated.
  • If conditionalExpression is false, expression2 is evaluated.

Example #7: C conditional Operator

#include <stdio.h>
int main(){
   char February;
   int days;
   printf("If this year is leap year, enter 1. If not enter any integer: ");
   scanf("%c",&February);

   // If test condition (February == 'l') is true, days equal to 29.
   // If test condition (February =='l') is false, days equal to 28. 
   days = (February == '1') ? 29 : 28;

   printf("Number of days in February = %d",days);
   return 0;
}
Output
If this year is leap year, enter 1. If not enter any integer: 1
Number of days in February = 29

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