Arduino Logic Tutorial: If, For, While, and Switch Case Statements

Arduino programming uses control structures such as if, for, while, and switch case to control decision-making and loops in a sketch. These structures allow the Arduino to respond to conditions, repeat tasks, and execute different blocks of code based on input.

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1. If Statement (Conditional Execution)

The if statement is used to execute a block of code only if a specified condition is met.

Syntax

if (condition) {
   // Code to execute if condition is true
}

Example: Turning an LED On Based on a Button Press

const int buttonPin = 2;  // Button connected to pin 2
const int ledPin = 13;    // LED connected to pin 13

void setup() {
    pinMode(buttonPin, INPUT);
    pinMode(ledPin, OUTPUT);
}

void loop() {
    int buttonState = digitalRead(buttonPin);  // Read button state

    if (buttonState == HIGH) {
        digitalWrite(ledPin, HIGH); // Turn LED on if button is pressed
    } else {
        digitalWrite(ledPin, LOW);  // Turn LED off otherwise
    }
}

If-Else Statement

if (temperature > 30) {
    Serial.println("It's too hot!");
} else {
    Serial.println("Temperature is normal.");
}

If-Else If Statement

if (temperature > 30) {
    Serial.println("It's too hot!");
} else if (temperature < 10) {
    Serial.println("It's too cold!");
} else {
    Serial.println("Temperature is comfortable.");
}

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2. For Loop (Repeating Tasks a Fixed Number of Times)

A for loop runs a block of code a fixed number of times. It is commonly used for iterating over arrays or controlling repetitive tasks.

Syntax

for (initialization; condition; increment) {
   // Code to execute in each iteration
}

Example: Blinking an LED 5 Times

const int ledPin = 13;

void setup() {
    pinMode(ledPin, OUTPUT);
}

void loop() {
    for (int i = 0; i < 5; i++) { // Loop runs 5 times
        digitalWrite(ledPin, HIGH);  // Turn LED on
        delay(500);  // Wait 500 ms
        digitalWrite(ledPin, LOW);   // Turn LED off
        delay(500);
    }
    delay(2000); // Pause before repeating
}

Example: Running Through an Array

int numbers[] = {1, 2, 3, 4, 5};

void setup() {
    Serial.begin(9600);
}

void loop() {
    for (int i = 0; i < 5; i++) {
        Serial.println(numbers[i]);  // Print each number in the array
    }
    delay(2000);
}

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3. While Loop (Repeating Until a Condition is Met)

A while loop runs a block of code as long as a specified condition remains true.

Syntax

while (condition) {
   // Code to execute while the condition is true
}

Example: Waiting for a Button Press

const int buttonPin = 2;

void setup() {
    pinMode(buttonPin, INPUT);
    Serial.begin(9600);
}

void loop() {
    Serial.println("Waiting for button press...");
    
    while (digitalRead(buttonPin) == LOW) {
        // Stay in loop until button is pressed
    }
    
    Serial.println("Button pressed!");
}

Example: Countdown Timer

int count = 10;

void setup() {
    Serial.begin(9600);
}

void loop() {
    while (count > 0) {
        Serial.print("Countdown: ");
        Serial.println(count);
        count--;
        delay(1000);
    }
    Serial.println("Liftoff!");
    delay(5000); // Restart countdown after delay
    count = 10;  // Reset count
}

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4. Switch Case (Handling Multiple Conditions Efficiently)

A switch case statement is used when multiple conditions need to be checked, making it an alternative to if-else if-else chains.

Syntax

switch (variable) {
    case value1:
        // Code to execute if variable == value1
        break;
    case value2:
        // Code to execute if variable == value2
        break;
    default:
        // Code to execute if none of the cases match
}

Example: Controlling an LED with a Rotary Switch

const int ledPin = 13;
int mode = 1;  // Example mode variable

void setup() {
    pinMode(ledPin, OUTPUT);
    Serial.begin(9600);
}

void loop() {
    switch (mode) {
        case 1:
            Serial.println("Mode 1: LED ON");
            digitalWrite(ledPin, HIGH);
            break;
        case 2:
            Serial.println("Mode 2: LED BLINKING");
            digitalWrite(ledPin, HIGH);
            delay(500);
            digitalWrite(ledPin, LOW);
            delay(500);
            break;
        case 3:
            Serial.println("Mode 3: LED OFF");
            digitalWrite(ledPin, LOW);
            break;
        default:
            Serial.println("Invalid Mode");
            break;
    }
}

Example: Using a Button to Cycle Through Modes

const int buttonPin = 2;
int mode = 1;

void setup() {
    pinMode(buttonPin, INPUT);
    Serial.begin(9600);
}

void loop() {
    if (digitalRead(buttonPin) == HIGH) {
        mode++;
        if (mode > 3) mode = 1;  // Reset mode to 1 if it exceeds 3
        delay(500);  // Debounce delay
    }

    switch (mode) {
        case 1:
            Serial.println("Mode 1: Low Power Mode");
            break;
        case 2:
            Serial.println("Mode 2: Normal Mode");
            break;
        case 3:
            Serial.println("Mode 3: High Performance Mode");
            break;
        default:
            Serial.println("Invalid Mode");
            break;
    }
}

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Conclusion

• if statements allow conditional execution based on sensor readings or button presses.
• for loops are useful for repetitive tasks with a known count, such as blinking an LED.
• while loops execute code continuously until a specific condition is met.
• switch case statements simplify decision-making when handling multiple conditions efficiently.

These structures enhance Arduino programming by making it easier to manage loops, conditions, and device control. 🚀