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Arithmetic Operators

An arithmetic operator performs mathematical operations such as addition, subtraction, multiplication, division etc 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

// 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 the variables a and b are integers. Hence, the output is also an integer. The compiler neglects the term after the decimal point and shows answer 2 instead of 2.25.

Suppose a = 5.0, b = 2.0, c = 5 and d = 2. Then in C programming,

// Either one of the operands is a floating-point number
a/b = 2.5  
a/d = 2.5  
c/b = 2.5  
// Both operands are integers
c/d = 2

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.

C 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

// 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 prefixes. These two operators can also be used as postfixes like a++ and a--.

If the increment operator is use as a prefix (++x), then the value of the variable is incremented before returning the value of the variable.e.g

int x = 5;

printf("%d", ++x); //Return 6 instead of 5

But if the increment operator is used as a suffix (x++), the value is returned first before incrementing. e.g:

int x = 5;

printf("%d", x++); //Return 5, then increase the value

Assignment Operators

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

// Working of assignment operators
#include <stdio.h>
int main()
{
    int a = 5, c;

    c = a;      // c is 5
    printf("c = %d\n", c);
    c += a;     // c is 10 
    printf("c = %d\n", c);
    c -= a;     // c is 5
    printf("c = %d\n", c);
    c *= a;     // c is 25
    printf("c = %d\n", c);
    c /= a;     // c is 5
    printf("c = %d\n", c);
    c %= a;     // c = 0
    printf("c = %d\n", c);

    return 0;
}

Output

c = 5 
c = 10 
c = 5 
c = 25 
c = 5 
c = 0

Comparison Operators

Comparison operators are binary operators that test a condition and return 1 if that condition is logically true and 0 if that condition is false.

Operator Operator name Example Description
== equal to a == b a is equal to b
!= not equal to a != b a is not equal to b
< less than a < b a is less than b
> greater than a > b a is greater than b
<= less than or equal to a <= b a is less than or equal to b
>= greater than or equal to a >= b a is greater than or equal to b

Let's take help of a code to understand the above concept:

int a, b;

a = 4;
b = 6;

a < b //true (return 1)
b < a //false (0)
a == b // false (0)
a = 6
a == b //true
Note the difference between the assignment operator (=) and the comparison operator (==)

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 Example
&& Logical 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)
! Logical NOT. True only if the operand is 0 If c = 5 then, expression !(c==5) equals to 0.

Example 5: Logical Operators

// 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) is %d \n", result);

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

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

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

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

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

    return 0;
}

Output

(a == b) && (c > b) is 1 
(a == b) && (c < b) is 0 
(a == b) || (c < b) is 1 
(a != b) || (c < b) is 0 
!(a != b) is 1 
!(a == b) is 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).

Others

Comma Operator

Comma operators are used to link related expressions together. For example:

int a, c = 5, d;

Sizeof

The sizeof operator is used to compute the size of its operand. it may look like a function, but it is actually an operator.

It returns an unsigned integer. Example:

#include <stdio.h>
int main()
{
    int a;
    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));

    return 0;
}

Output

Size of int = 4 bytes
Size of float = 4 bytes
Size of double = 8 bytes
Size of char = 1 byte

We can also pass a data type to the sizeof operator. It simply returns the amount the amount of memory allocated for that data type. e.g:

sizeof(int); //4
sizeof(char); //1

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