C-Operators.md – C Operators: Arithmetic, Logical, Conditional and more

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).

Operator	Meaning 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--. Visit this page to learn more on how increment and decrement operators work when used as postfix.

C Assignment Operators

An assignment operator is used for assigning a value to a variable. The most common assignment operator is =

Operator	Example	Same as
=	a = b	a = b
+=	a += b	a = a+b
-=	a -= b	a = a-b
*=	a *= b	a = a*b
/=	a /= b	a = a/b
%=	a %= b	a = 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 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](/c-programming/c-for-loop “C for loop”.html).

Operator	Meaning of Operator	Example
==	Equal to	5 == 3 returns 0
>	Greater than	5 > 3 returns 1
<	Less than	5 < 3 returns 0
!=	Not equal to	5 != 3 returns 1
>=	Greater than or equal to	5 >= 3 returns 1
<=	Less than or equal to	5 <= 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.

Operator	Meaning of Operator	Example
&&	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 true	If c = 5 and d = 2 then, expression `((c == 5) \|\| (d > 5))` equals to 1.
!	Logical NOT. True only if the operand is 0	If 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.

Operators	Meaning 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

Other operators such as & (reference operator), * (dereference operator) and -> (member selection) operator will be discussed in C pointers.