📘 Operators

🎯 Lesson Objective

By the end of this lesson, students will:

• Understand what operators are

• Learn arithmetic operators

• Learn comparison operators

• Learn logical operators

• Understand assignment operators

• Use operators to build automation logic

1️⃣ What is an Operator?

An operator is a symbol that performs an operation on variables or values.

Example:

Here:
+ is an operator.

It performs addition.

Operators allow the program to process data.

2️⃣ Types of Operators in Arduino / C++

There are 4 main types we will focus on:

1️⃣ Arithmetic Operators
2️⃣ Comparison Operators
3️⃣ Logical Operators
4️⃣ Assignment Operators

🔹 3️⃣ Arithmetic Operators

Used for mathematical calculations.

📌 Example 1 – Basic Math

int a = 10;
int b = 3;

int sum = a + b; // 13
int diff = a - b; // 7
int product = a * b; // 30
int division = a / b; // 3
int remainder = a % b; // 1

Important:

Integer division removes decimals.

10 / 3 = 3 (not 3.33)

If you want decimal result → use float.

📌 Real IoT Example

Water Tank Level Percentage:

int level = 300;
int maxLevel = 500;

int percentage = (level * 100) / maxLevel;

Operators allow real-time calculation.

🔹 4️⃣ Assignment Operators

Used to assign values.

🔹 Basic Assignment

= means “store value”.

🔹 Short Assignment Operators

📌 Example

int counter = 0;

counter += 1; // counter = counter + 1
counter -= 2;

Very useful in loops.

🔹 5️⃣ Comparison Operators

Used for decision-making.

They compare values and return:

true or false

📌 Example

int temperature = 32;

if (temperature > 30) {
Serial.println("AC ON");
}

Comparison returns:

true → Execute block
false → Skip block

⚠️ Important

Do not confuse:

= → Assignment
== → Comparison

Wrong:

Correct:

🔹 6️⃣ Logical Operators

Used to combine multiple conditions.

🔹 AND Operator (&&)

Both conditions must be true.

Example:

if (temperature > 30 && gasLevel > 500)

Means:

Temperature must be high
AND
Gas level must be high

🔹 OR Operator (||)

At least one condition must be true.

Example:

Either condition triggers action.

🔹 NOT Operator (!)

Reverses condition.

Example:

Means:

If pump is NOT ON.

🔟 Combining Operators – Real IoT Example

Smart Home Logic:

if (manualMode == false && temperature > setPoint) {
digitalWrite(relayPin, HIGH);
}

Breakdown:

manualMode must be false
AND
temperature must be above setPoint

Then turn AC ON.

This is real automation logic.

1️⃣1️⃣ Order of Operations

Mathematical operations follow order:

1. Parentheses

2. Multiplication / Division

3. Addition / Subtraction

Example:

Result = 14
Not 20

Use parentheses for clarity:

Result = 20

1️⃣2️⃣ Modulus Operator (%) – Useful in IoT

Returns remainder.

Example:

Useful for:

• Blinking patterns

• Repeating sequences

• Time-based logic

1️⃣3️⃣ Increment & Decrement Operators

Shortcut operators:

Example:

Very useful in loops.

1️⃣4️⃣ Real Debug Example

int gasValue = 800;

if (gasValue >= 700) {
Serial.println("Gas Alert!");
}

Comparison operator triggers alert.

Operators make sensors meaningful.

1️⃣5️⃣ Common Beginner Mistakes

❌ Using = instead of ==
❌ Forgetting parentheses
❌ Mixing && and || incorrectly
❌ Integer division mistake
❌ Not understanding operator priority

Always test with Serial Monitor.

📌 Lesson Summary

In this lesson, we learned:

• What operators are

• Arithmetic operators

• Assignment operators

• Comparison operators

• Logical operators

• Real IoT logic building

• Common mistakes

Operators are the foundation of automation.

Without operators:
No decision-making.