CHow-ToBeginner · 3 min read

How to Use Arithmetic Operators in C: Syntax and Examples

In C, you use arithmetic operators like +, -, *, /, and % to perform basic math operations on numbers. These operators work with variables and constants to add, subtract, multiply, divide, or find the remainder of integer division.

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Syntax

Arithmetic operators in C are used between two operands (numbers or variables) to perform calculations. The main operators are:

+ for addition
- for subtraction
* for multiplication
/ for division
% for modulus (remainder of division)

Example syntax: result = a + b; means add a and b and store the result.

result = a + b;
result = a - b;
result = a * b;
result = a / b;
result = a % b;

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Example

This example shows how to use all basic arithmetic operators with integer variables and print the results.

#include <stdio.h>

int main() {
    int a = 10, b = 3;
    printf("a = %d, b = %d\n", a, b);
    printf("Addition: a + b = %d\n", a + b);
    printf("Subtraction: a - b = %d\n", a - b);
    printf("Multiplication: a * b = %d\n", a * b);
    printf("Division: a / b = %d\n", a / b);
    printf("Modulus: a %% b = %d\n", a % b);
    return 0;
}

Output

a = 10, b = 3 Addition: a + b = 13 Subtraction: a - b = 7 Multiplication: a * b = 30 Division: a / b = 3 Modulus: a % b = 1

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Common Pitfalls

Common mistakes when using arithmetic operators in C include:

Using / with integers results in integer division, which drops the decimal part.
Dividing by zero causes a runtime error.
Using % with non-integers is not allowed.
For floating-point division, at least one operand must be a float or double.

Example of integer division vs floating-point division:

#include <stdio.h>

int main() {
    int a = 7, b = 2;
    printf("Integer division: 7 / 2 = %d\n", a / b); // result is 3

    double x = 7.0, y = 2.0;
    printf("Floating-point division: 7.0 / 2.0 = %.2f\n", x / y); // result is 3.50

    // Wrong: double z = a % b; // error: modulus with float
    return 0;
}

Output

Integer division: 7 / 2 = 3 Floating-point division: 7.0 / 2.0 = 3.50

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Quick Reference

Operator	Description	Example	Result
+	Addition	5 + 3	8
-	Subtraction	5 - 3	2
*	Multiplication	5 * 3	15
/	Division (integer if both operands int)	5 / 3	1
%	Modulus (remainder of integer division)	5 % 3	2

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Key Takeaways

Use +, -, *, /, and % to perform basic math operations in C.

Integer division drops decimals; use float or double for precise division.

Modulus % works only with integers and gives the remainder.

Avoid dividing by zero to prevent runtime errors.

Always match operand types to get expected results.