nt a = 2;
int b = 7;
int sum;

sum = a + b;

sum = a + b;

int sum;

sum = 2 + 10;

int a = 3;
int sum;

sum = a + 24;

int result;

result = 10 - 2;

 nt result;

result = 4 * 3;

int result;

result = 12 / 3;

 int result;

result = 5 / 4;

float result;

result = 5.0 / 4.0;

int result;

result = 11 % 4;

 void setup() {
  int a = 2;
  int b = 7;
  int result;
  float result_fl;
  
  Serial.begin(9600);
  
  Serial.print("Addition (a + b): ");
  result = a + b;
  Serial.println(result);
  
  Serial.print("Subtraction (10 - 2): ");
  result = 10 - 2;
  Serial.println(result);
  
  Serial.print("Multiplication (4 * 3): ");
  result = 4 * 3;
  Serial.println(result);
  
  Serial.print("Int Division (5 / 4): ");
  result = 5 / 4;
  Serial.println(result);
  
  Serial.print("Float Division (5.0 / 4.0): ");
  result_fl = 5.0 / 4.0;
  Serial.println(result_fl);
  
  Serial.print("Remainder (11 % 4): ");
  result = 11 % 4;
  Serial.println(result);
}

void loop() {
}

 void setup() {
  Serial.begin(9600);
  
  Serial.print("Is 7 greater than 5? ");
  Serial.println(7 > 5);
  
  Serial.print("Is 7 less than 5? ");
  Serial.println(7 < 5);
}

void loop() {
}

 int a = 2;
int b = 3;

Serial.println(a > b);

 int a = 2;
int b = 3;

Serial.println(a < b);

void setup() {
  int a = 2;
  int b = 3;
  
  Serial.begin(9600);
  
  Serial.print("Is a greater than b? ");
  Serial.println(a > b);
  
  Serial.print("Is a less than 25? ");
  Serial.println(a < 25);
  
  Serial.print("Is a greater than or equal to b? ");
  Serial.println(a >= b);
  
  a = 3;
  Serial.print("Is a greater than or equal to b? ");
  Serial.println(a >= b);
  
  a = 4;
  Serial.print("Is a greater than or equal to b? ");
  Serial.println(a >= b);
  
  Serial.print("Is a equal to b? ");
  Serial.println(a == b);
  
  b = 4;
  Serial.print("Is a equal to b? ");
  Serial.println(a == b);
  
}

void loop() {
}

void setup() {
  int a = 2;
  int b = 3;
  
  Serial.begin(9600);
  
  Serial.print("a + b = ");
  Serial.println(a + b);
}

void loop() {
}

void setup() {
  int a = 2;
  int b = 3;
  
  Serial.begin(9600);
  
  Serial.print("a == b: ");
  Serial.println(a == b);
  
  Serial.print("a = b: ");
  Serial.println(a = b);
}

void loop() {
}

void setup() {
  int count = 0;
  
  Serial.begin(9600);
  
  Serial.println(count++);
  Serial.println(count++);
  Serial.println(count++);
  
  Serial.println(count);
}

void loop() {
}

void setup() {
  int count = 0;
  
  Serial.begin(9600);
  
  Serial.println(count);
  count++;
  Serial.println(count);
  count++;
  Serial.println(count);
  count++;
  
  Serial.println(count);
}

void loop() {
}

 Serial.println(count++);

Serial.println(count);
count++;

 /*
    Sketch Name:  comments
    
    Purpose:      Demonstrates how to use comments.
                  Increments and displays a number in the main loop.
    
    Date:             
    Author:       
*/

void setup() {
  Serial.begin(9600);       // use the serial port for printing the number
}

int count = 0;              // the number to print

void loop() {
  Serial.println(count++);  // print and increment the number
  delay(1000);              // 1 second delay between printing
}

 delay(1000);  /* 1 second delay between printing */

// the delay slows down the printing of the numbers
delay(1000);  // 1 second delay between printing

void setup() {
  int i;
  
  Serial.begin(9600);
  
  for (i = 0; i < 10; i++) {
    Serial.print("i = ");
    Serial.println(i);
  }
}

void loop() {
}

for () {
}

i is initialized to 0
i contains 0
i < 10 evaluates to true or 1 because i is less than 10
The two statements in the loop run, print i as 0
At the end of the loop i is incremented so i == 1

i is not initialized again
i contains 1
i < 10 evaluates to true or 1 because i is less than 10
The two statements in the loop run, print i as 1
At the end of the loop i is incremented so i == 2

i is not initialized again
i contains 9
i < 10 evaluates to true or 1 because i is less than 10
The two statements in the loop run, print i as 9
At the end of the loop i is incremented so i == 10

 i is not initialized again
i contains 10
i < 10 evaluates to false or 0 because i is not less than 10 (it is equal to 10)
The statements in the loop are not run again
The loop is exited
The statement below the closing bracket of the loop will be run

 void setup() {
  Serial.begin(9600);
  
  for (int i = 0; i < 10; i++) {
    Serial.print("i = ");
    Serial.println(i);
  }
}

void loop() {
}

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

void loop() {
  for (int i = 0; i < 10; i++) {
    Serial.print("i = ");
    Serial.println(i);
  }
  delay(1000);
}

void setup() {
  int i = 0;
  
  Serial.begin(9600);
  
  while (i < 10) {
    Serial.print("i = ");
    Serial.println(i);
    i++;
  }
}

void loop() {
}

while (loop test expression goes here) {
  Statements that run in the loop go here
  Statement 1
  Statement 2
  ...
}

void setup() {
  int sum = 0;
  
  Serial.begin(9600);
  
  // count up to 25 in 5s
  while (sum < 25) {
    sum = sum + 5;
    Serial.print("sum = ");
    Serial.println(sum);
    delay(500);                // 500ms delay
  }
}

void loop() {
}

sum = sum + 5;

 do {
    Statements that run in the loop go here
    Statement 1
    Statement 2
    ...
} while (test expression goes here);

 void setup() {
  int sum = 0;
  
  Serial.begin(9600);
  
  // count up to 25 in 5s
  do {
    sum = sum + 5;
    Serial.print("sum = ");
    Serial.println(sum);
    delay(500);                // 500ms delay
  } while (sum < 25);
}

void loop() {
}

void setup() {
  int sum = 25;
  
  Serial.begin(9600);
  
  // count up to 25 in 5s
  do {
    sum = sum + 5;
    Serial.print("sum = ");
    Serial.println(sum);
    delay(500);                // 500ms delay
  } while (sum < 25);
}

void loop() {
}

 void setup() {
  int sum = 25;
  
  Serial.begin(9600);
  
  // count up to 25 in 5s
  while (sum < 25) {
    sum = sum + 5;
    Serial.print("sum = ");
    Serial.println(sum);
    delay(500);                // 500ms delay
  }
}

void loop() {
}

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

void loop() {
  char rx_byte;
  
  if (Serial.available() > 0) {    // is a character available?
    rx_byte = Serial.read();       // get the character
    Serial.print("You typed: ");
    Serial.println(rx_byte);
  }
}

if (conditional expression) {
  Body of if statement
}

rx_byte = Serial.read();       // get the character

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);  // LED on pin 13 of UNO
}

void loop() {
  char rx_byte;
  
  if (Serial.available() > 0) {    // is a character available?
    rx_byte = Serial.read();
    if (rx_byte == 'a') {
      digitalWrite(13, HIGH);
    }
  }
}

 if (rx_byte == 'a')

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);  // LED on pin 13 of UNO
}

void loop() {
  char rx_byte;
  
  if (Serial.available() > 0) {    // is a character available?
    rx_byte = Serial.read();       //
    if (rx_byte == 'a') {
      digitalWrite(13, HIGH);
    }
    if (rx_byte == 'b') {
      digitalWrite(13, LOW);
    }
  }
}

if (conditional expression) {
}

else {
}

// "if" statement
if (conditional expression) {
  // Code placed here only runs if conditional expression is true
}

// Whether the conditional expression evaluates to true or false,
// code placed here will run

// "if-else" construct
if (conditional expression) {
  // Body of the "if" statement between { and }
  // Works as a normal "if" statement, code placed here will only
  // run if the conditional expression evaluates to true
}

else {
  // Body of the "else" statement between { and }
  // Code placed here will always run if the conditional expression
  // from the "if" statement evaluates to false
}

// Code placed below the if-else construct will always run whether
// the conditional expression evaluated to true or false

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);  // LED on pin 13 of UNO
}

void loop() {
  char rx_byte;
  
  if (Serial.available() > 0) {    // is a character available?
    rx_byte = Serial.read();
    if (rx_byte == 'a') {
      // switch the LED on if the character 'a' is received
      digitalWrite(13, HIGH);
    }
    else {
      // switch the LED off if any character except 'a' is received
      digitalWrite(13, LOW);
    }
  }
}

if (rx_byte == 'a') {
  // switch the LED on if the character 'a' is received
  digitalWrite(13, HIGH);
}
else {
  // switch the LED off if any character except 'a' is received
  digitalWrite(13, LOW);
}

 if (Serial.available() > 0) {    // is a character available?
}

if (conditional expression 1) {
}
else if (conditional expression 2) {
}

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);  // LED on pin 13 of UNO
}

char rx_byte = 0;

void loop() {
  if (Serial.available() > 0) {    // is a character available?
    rx_byte = Serial.read();
  }
  if (rx_byte == 'a') {
    digitalWrite(13, HIGH);
    delay(500);
    digitalWrite(13, LOW);
    delay(500);
  }
  else if (rx_byte == 'b') {
    digitalWrite(13, HIGH);
    delay(200);
    digitalWrite(13, LOW);
    delay(200);
  }
}

if (rx_byte == 'a') {
  digitalWrite(13, HIGH);
  delay(500);
  digitalWrite(13, LOW);
  delay(500);
}
else if (rx_byte == 'b') {
  digitalWrite(13, HIGH);
  delay(200);
  digitalWrite(13, LOW);
  delay(200);
}

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);  // LED on pin 13 of UNO
}

char rx_byte = 0;

void loop() {
  if (Serial.available() > 0) {    // is a character available?
    rx_byte = Serial.read();
  }
  if (rx_byte == 'a') {
    // the character 'a' was received, blink the LED once per second
    digitalWrite(13, HIGH);  // switch the LED on
    delay(500);              // leave the LED on for 500ms
    digitalWrite(13, LOW);   // switch the LED off
    delay(500);              // leave the LED off for 500ms
  }
  else if (rx_byte == 'b') {
    // the character 'b' was received, blink the LED every 400ms
    digitalWrite(13, HIGH);  // switch the LED on
    delay(200);              // leave the LED on for 200ms
    digitalWrite(13, LOW);   // switch the LED off
    delay(200);              // leave the LED off for 200ms
  }
  else {
    // any character except 'a' or 'b' was received
    digitalWrite(13, HIGH);  // switch the LED on
    delay(100);              // leave the LED on for 100ms
    digitalWrite(13, LOW);   // switch the LED off
    delay(100);              // leave the LED off for 100ms
  }
}

char rx_byte = 'a';

if (conditional expression 1) {
}
else if (conditional expression 2) {
}
else if (conditional expression 3) {
}
else if (conditional expression 4) {
}
etc. ...

 if (conditional expression 1) {
}
else if (conditional expression 2) {
}
else if (conditional expression 3) {
}
else if (conditional expression 4) {
}
else {
}