C Arithmetic Operators: Beginner's Guide

In C programming, arithmetic operators are used to perform basic mathematical operations like addition, subtraction, multiplication, division, and modulus.

Let’s walk through them with clear explanations and real code examples.

What Are Arithmetic Operators in C?

Arithmetic operators work on numeric data types (int, float, double) to perform mathematical operations. These are some of the most frequently used operators in any program.

List of Arithmetic Operators

Operator	Name	Description	Example	Result
`+`	Addition	Adds two values	`5 + 3`	`8`
`-`	Subtraction	Subtracts right from left	`5 - 3`	`2`
`*`	Multiplication	Multiplies two values	`5 * 3`	`15`
`/`	Division	Divides left by right	`5 / 2`	`2` (int) or `2.5` (float)
`%`	Modulus	Returns remainder (integers only)	`5 % 2`	`1`

Example Program: Arithmetic in C

#include <stdio.h>

int main() {
    int a = 10, b = 3;

    printf("Addition: %d + %d = %d\n", a, b, a + b);
    printf("Subtraction: %d - %d = %d\n", a, b, a - b);
    printf("Multiplication: %d * %d = %d\n", a, b, a * b);
    printf("Division: %d / %d = %d\n", a, b, a / b);
    printf("Modulus: %d %% %d = %d\n", a, b, a % b);

    return 0;
}

✅ Output:

🧠 Note: For int / int, the result is also an integer. Use type casting for decimal division.

Example: Division with Type Casting

#include <stdio.h>

int main() {
    int x = 5, y = 2;
    float result = (float)x / y;

    printf("Division (float): %.2f\n", result); // Output: 2.50

    return 0;
}

✅ Best Practices

Tip	Reason
Use `(float)` for accurate division	Prevents integer truncation
Avoid modulus with float types	`%` only works with integers
Check divisor before division	Prevent division by zero error

❌ Common Mistakes to Avoid

Mistake	Problem
`5 / 2 = 2.5` (wrong)	Result is 2 if both are int
`5.0 % 2` (invalid)	Modulus only works on ints
Division by zero	Runtime error

Arithmetic Operator Precedence

When combining operators, precedence rules apply (like in math):

*, /, % (evaluated left to right)
+, - (evaluated left to right)

Use parentheses () to force evaluation order.

✅ Example:

int result = 10 + 5 * 2; // result = 20
int fixed = (10 + 5) * 2; // fixed = 30