Loop Arduino

 The loop provides a mechanism to repeat a section of code depending on the value of a variable. So you set the initial value of the variable, the condition to exit the loop, and the action on the variable each time around the loop. A loop statement also will allow to execute a statement or group of statements several times and following is the general form of a loop statement in most of the programming language.

Types of loops

while loop

while loops will loop continuously, and infinitely until the expression inside the () becomes false.

Syntax:

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

Example:

In the example sketch below, the while loop is used to count up to a hundred in tens by adding ten to a variable each time through the loop.

void setup() {
  int time = 0;
 
  Serial.begin(9600);
 
  // count up to 100 in 10s
  while (time < 100) {
    time = time + 10;
    Serial.print("time = ");
    Serial.println(time);
    delay(10000);  // 1000ms delay
  }
}

void loop() {
}

do…while loop

The do-while loop is similar as it waits for the event, but there are certain differences: the while loop is executed while the condition is being fulfilled, whereas the do-while is executed at least once after the condition has been fulfilled.

Syntax:

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

Example (Sketch)

void setup() {
  int time= 0;
  
  Serial.begin(9600);
  
  // count up to 100 in 10s
  do {
    time= time+ 10;
    Serial.print("time= ");
    Serial.println(time);
    delay(1000);                // 1000ms delay
  } while (sum < 100);
}

void loop() {
}

for loop

A for loop executes statements a predetermined number of times. The control expression for the loop is initialized, tested and manipulated entirely within the for loop parentheses.

You can create a for loop that counts down by changing all three parameters in the for loop. Lets say you want to count down from 10 to 1 (ten iterations round the loop).

Sketch

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

void loop() {
}

Nested loop

allows you to use loop statement inside another loop