Operators in C

Operators in C are special symbols used to perform operations on variables, constants, and expressions. They form the foundation of programming logic by enabling arithmetic calculations, comparisons, logical decisions, memory access, and bit-level manipulations.

• C supports arithmetic, relational, logical, bitwise, assignment, and special operators.
• Operators can be unary, binary, or ternary based on the number of operands.

#include <stdio.h>
int main() {
    
    // Expression for getting sum
    int sum = 10 + 20;
    
    printf("%d", sum);
    return 0;
}

30

Types of Operators in C

C language provides a wide range of built in operators that can be classified into 6 types based on their functionality:

1. Arithmetic Operators

The arithmetic operators are used to perform mathematical calculations such as addition, subtraction, multiplication, division, and modulus on numeric values.

• Work with integer and floating-point data types.
• Include unary operators like increment (++) and decrement (--)

#include <stdio.h>

int main() {

    int a = 25, b = 5;

    // using operators and printing results
    printf("a + b = %d\n", a + b);
    printf("a - b = %d\n", a - b);
    printf("a * b = %d\n", a * b);
    printf("a / b = %d\n", a / b);
    printf("a %% b = %d\n", a % b);
    printf("+a = %d\n", +a);
    printf("-a = %d\n", -a);
    printf("a++ = %d\n", a++);
    printf("a-- = %d\n", a--);

    return 0;
}

a + b = 30
a - b = 20
a * b = 125
a / b = 5
a % b = 0
+a = 25
-a = -25
a++ = 25
a-- = 26

2.Relational Operators

The relational operators compare two values and determine the relationship between them. The result of a relational operation is either true (1) or false (0).

• Return boolean-like results (0 or 1).
• Used in decision-making statements.

#include <stdio.h>

int main() {
    int a = 25, b = 5;

    // using operators and printing results
    printf("a < b  : %d\n", a < b);
    printf("a > b  : %d\n", a > b);
    printf("a <= b: %d\n", a <= b);
    printf("a >= b: %d\n", a >= b);
    printf("a == b: %d\n", a == b);
    printf("a != b : %d\n", a != b);

    return 0;
}

a < b  : 0
a > b  : 1
a <= b: 0
a >= b: 1
a == b: 0
a != b : 1

Here, 0 means false and 1 means true.

3.Logical Operator

Logical Operators are used to combine multiple conditions or reverse a condition's result. They evaluate expressions and return either true or false.

• Return logical results (true or false).
• Support AND (&&), OR (||), and NOT (!) operations.

#include <stdio.h>

int main() {
    int a = 25, b = 5;

    // using operators and printing results
    printf("a && b : %d\n", a && b);
    printf("a || b : %d\n", a || b);
    printf("!a: %d\n", !a);

    return 0;
}

a && b : 1
a || b : 1
!a: 0

4.Bitwise Operators

The Bitwise operators perform operations directly on the binary representation of integers. They are widely used in low-level programming and performance-critical applications.

• Useful for flags, masks, and hardware programming.
• Generally faster than equivalent arithmetic operations.

Note: Mathematical operations such as addition, subtraction, multiplication, etc. can be performed at the bit level for faster processing.

#include <stdio.h>

int main() {
    int a = 25, b = 5;

    // using operators and printing results
    printf("a & b: %d\n", a & b);
    printf("a | b: %d\n", a | b);
    printf("a ^ b: %d\n", a ^ b);
    printf("~a: %d\n", ~a);
    printf("a >> b: %d\n", a >> b);
    printf("a << b: %d\n", a << b);

    return 0;
}

a & b: 1
a | b: 29
a ^ b: 28
~a: -26
a >> b: 0
a << b: 800

5. Assignment Operators

Assignment operators are used to assign values to variables. Compound assignment operators combine assignment with another operation, making code shorter and more readable.

• Simplify expressions using compound operators.
• Improve code readability.

#include <stdio.h>

int main() {
    int a = 25, b = 5;

    // using operators and printing results
    printf("a = b: %d\n", a = b);
    printf("a += b: %d\n", a += b);
    printf("a -= b: %d\n", a -= b);
    printf("a *= b: %d\n", a *= b);
    printf("a /= b: %d\n", a /= b);
    printf("a %%= b: %d\n", a %= b);
    printf("a &= b: %d\n", a &= b);
    printf("a |= b: %d\n", a |= b);
    printf("a ^= b: %d\n", a ^= b);
    printf("a >>= b: %d\n", a >>= b); 
    printf("a <<= b: %d\n", a <<= b);

    return 0;
}

a = b: 5
a += b: 10
a -= b: 5
a *= b: 25
a /= b: 5
a %= b: 0
a &= b: 0
a |= b: 5
a ^= b: 0
a >>= b: 0
a <<= b: 0

Other Operators

Apart from the above operators, there are some other operators available in C used to perform some specific tasks. Some of them are discussed here: 

1. sizeof Operator

sizeof is much used in the C programming language. It is a compile-time unary operator which can be used to compute the size of its operand.

Syntax

sizeof (operand)

2. Comma Operator ( , )

The comma operator (represented by the token) is a binary operator that evaluates its first operand and discards the result, it then evaluates the second operand and returns this value (and type).

Syntax

operand1 , operand2

3. Conditional Operator ( ? : )

The conditional operator is the only ternary operator in C. It is a conditional operator that we can use in place of if..else statements.

Syntax

expression1 ? Expression2 : Expression3;

Here, Expression1 is the condition to be evaluated. If the condition(Expression1) is True then we will execute and return the result of Expression2 otherwise if the condition(Expression1) is false then we will execute and return the result of Expression3.

4. dot (.) and arrow (->) Operators

Member operators are used to reference individual members of classes, structures, and unions.

• The dot operator is applied to the actual object. 
• The arrow operator is used with a pointer to an object.

Syntax

structure_variable . member;
structure_pointer -> member;

5. Cast Operators

Casting operators convert one data type to another. For example, (int)2.2000 would return 2. A cast is a special operator that forces one data type to be converted into another. 

Syntax

(new_type) operand;

6. addressof (&) and Dereference (*) Operators

Addressof operator & returns the address of a variable and the dereference operator * is used to access the value stored at that address.

Example of Other C Operators

#include <stdio.h>

int main()
{
    // integer variable
    int num = 10;
    int* add_of_num = &num;

    printf("sizeof(num) = %d bytes\n", sizeof(num));
    printf("&num = %p\n", &num);
    printf("*add_of_num = %d\n", *add_of_num);
    printf("(10 < 5) ? 10 : 20 = %d\n", (10 < 5) ? 10 : 20);
    printf("(float)num = %f\n", (float)num);

    return 0;
}

sizeof(num) = 4 bytes
&num = 0x7ffdb58c037c
*add_of_num = 10
(10 < 5) ? 10 : 20 = 20
(float)num = 10.000000

Related article: Operator Precedence and Associativity