# 10 - C Operators - Mathematical and Logical Operations
**URL:** https://buzzly.harislab.tech/t/10-c-operators-mathematical-and-logical-operations/198
**Category:** C Programming Tutorials
**Tags:** c, basics
**Created:** [April 21, 2026, 2:48pm UTC](https://buzzly.harislab.tech/t/10-c-operators-mathematical-and-logical-operations/198 "2026-04-21T14:48:18Z")
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### Author:  [@Haris](https://buzzly.harislab.tech/u/Haris)
#### Post date: [April 21, 2026, 2:48pm UTC](https://buzzly.harislab.tech/t/10-c-operators-mathematical-and-logical-operations/198/1 "2026-04-21T14:48:18Z")
**Learn about arithmetic, comparison, and logical operators in C**
* * *
## What is this topic?
This guide explains C Operators - Mathematical and Logical Operations in simple terms, what it does, and how to use it in real C programs.
## Why We Need It
- It helps you write correct and reliable C code.
- It makes your programs easier to read and maintain.
- It is used in real projects and interviews.
- It reduces common beginner mistakes.
- It builds a strong foundation for advanced topics.
## Use Cases
- Building practical C programs step by step.
- Solving real coding tasks with clean logic.
- Preparing for exams, interviews, and projects.
- Understanding and improving existing C code.
* * *
## What Are Operators?
Operators are symbols that perform operations on values. Think of them like mathematical symbols: +, -, \*, /.
* * *
## Arithmetic Operators
Used for mathematical calculations.
| Operator | Name | Example | Result |
| --- | --- | --- | --- |
| `+` | Addition | `5 + 3` | `8` |
| `-` | Subtraction | `5 - 3` | `2` |
| `*` | Multiplication | `5 * 3` | `15` |
| `/` | Division | `6 / 2` | `3` |
| `%` | Modulus (remainder) | `7 % 3` | `1` |
### Examples
```c
#include
int main() {
int x = 10;
int y = 3;
printf("%d + %d = %d\n", x, y, x + y); // 13
printf("%d - %d = %d\n", x, y, x - y); // 7
printf("%d * %d = %d\n", x, y, x * y); // 30
printf("%d / %d = %d\n", x, y, x / y); // 3
printf("%d %% %d = %d\n", x, y, x % y); // 1
return 0;
}
```
**Output:**
```auto
10 + 3 = 13
10 - 3 = 7
10 * 3 = 30
10 / 3 = 3
10 % 3 = 1
```
* * *
## Comparison Operators
Compare two values and return true (1) or false (0).
| Operator | Name | Example | Result |
| --- | --- | --- | --- |
| `==` | Equal to | `5 == 5` | `1` (true) |
| `!=` | Not equal to | `5 != 3` | `1` (true) |
| `>` | Greater than | `5 > 3` | `1` (true) |
| `<` | Less than | `5 < 3` | `0` (false) |
| `>=` | Greater or equal | `5 >= 5` | `1` (true) |
| `<=` | Less or equal | `5 <= 3` | `0` (false) |
### Examples
```c
#include
int main() {
int age = 18;
printf("age == 18: %d\n", age == 18); // 1 (true)
printf("age != 18: %d\n", age != 18); // 0 (false)
printf("age > 17: %d\n", age > 17); // 1 (true)
printf("age < 21: %d\n", age < 21); // 1 (true)
printf("age >= 18: %d\n", age >= 18); // 1 (true)
printf("age <= 18: %d\n", age <= 18); // 1 (true)
return 0;
}
```
* * *
## Logical Operators
Combine multiple conditions.
| Operator | Name | Meaning |
| --- | --- | --- |
| `&&` | AND | Both conditions true |
| `||` | OR | At least one true |
| `!` | NOT | Opposite result |
### AND (&&)
```c
int age = 25;
int income = 50000;
if (age > 18 && income > 40000) {
printf("Eligible for loan\n"); // Both true, so this runs
}
```
### OR (||)
```c
int day = 6; // Saturday
if (day == 6 || day == 7) {
printf("It's the weekend!\n"); // At least one true
}
```
### NOT (!)
```c
int isRaining = 0; // 0 means false
if (!isRaining) {
printf("Let's go outside!\n"); // Opposite of 0 is 1 (true)
}
```
* * *
## Assignment Operators
Assign values to variables.
| Operator | Example | Equivalent |
| --- | --- | --- |
| `=` | `x = 5` | Assign 5 to x |
| `+=` | `x += 5` | `x = x + 5` |
| `-=` | `x -= 5` | `x = x - 5` |
| `*=` | `x *= 5` | `x = x * 5` |
| `/=` | `x /= 5` | `x = x / 5` |
| `%=` | `x %= 5` | `x = x % 5` |
### Examples
```c
int x = 10;
x += 5; // x is now 15
printf("%d\n", x);
x -= 3; // x is now 12
printf("%d\n", x);
x *= 2; // x is now 24
printf("%d\n", x);
```
* * *
## Increment and Decrement
| Operator | Meaning | Example |
| --- | --- | --- |
| `++` | Increment by 1 | `x++` or `++x` |
| `--` | Decrement by 1 | `x--` or `--x` |
### Examples
```c
int count = 5;
count++;
printf("%d\n", count); // 6
count--;
printf("%d\n", count); // 5
```
* * *
## Practical Example
```c
#include
int main() {
// Shopping calculation
float itemPrice = 29.99;
int quantity = 3;
const float TAX = 0.08;
float subtotal = itemPrice * quantity;
float tax = subtotal * TAX;
float total = subtotal + tax;
printf("Item Price: $%.2f\n", itemPrice);
printf("Quantity: %d\n", quantity);
printf("Subtotal: $%.2f\n", subtotal);
printf("Tax (8%%): $%.2f\n", tax);
printf("Total: $%.2f\n", total);
// Check if discount applies
int discount = (total >= 100) ? 10 : 0;
printf("Discount: $%d\n", discount);
return 0;
}
```
* * *
## Operator Precedence
Order of operations matters:
```c
int result = 5 + 3 * 2; // 11, not 16
// Multiplication happens first: 3 * 2 = 6
// Then addition: 5 + 6 = 11
```
Use parentheses to be clear:
```c
int result1 = 5 + 3 * 2; // 11
int result2 = (5 + 3) * 2; // 16
```
* * *
## Quick Reference
```c
// Arithmetic
int sum = 10 + 5; // 15
int product = 10 * 5; // 50
// Comparison
int equal = (10 == 10); // 1 (true)
int greater = (10 > 5); // 1 (true)
// Logical
int both = (1 && 1); // 1 (true)
int either = (0 || 1); // 1 (true)
int opposite = !0; // 1 (true)
// Assignment
int x = 5;
x += 3; // x is now 8
x++; // x is now 9
```
* * *
## Practice Exercise
Create `operators.c`:
```c
#include
int main() {
int num1 = 20;
int num2 = 8;
printf("=== Arithmetic ===\n");
printf("%d + %d = %d\n", num1, num2, num1 + num2);
printf("%d - %d = %d\n", num1, num2, num1 - num2);
printf("%d * %d = %d\n", num1, num2, num1 * num2);
printf("%d / %d = %d\n", num1, num2, num1 / num2);
printf("%d %% %d = %d\n", num1, num2, num1 % num2);
printf("\n=== Comparison ===\n");
printf("%d > %d: %d\n", num1, num2, num1 > num2);
printf("%d < %d: %d\n", num1, num2, num1 < num2);
printf("%d == %d: %d\n", num1, num2, num1 == num2);
return 0;
}
```
* * *
### 📚 Navigation
| Previous | Next |
| --- | --- |
| [← C Constants](https://buzzly.harislab.tech/t/09-c-constants-creating-fixed-values/197/1) | C Booleans → |
* * *
## ❓ Have Questions?
**Comment below and we’ll help you!** Need help with operators? Ask in the comments!
* * *
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