Control Structure

break

it is used to exit from loop conditions or switch statement.

Example

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int threshold = 40;
for (int x = 0; x < 255; x++) {
  analogWrite(PWMpin, x);
  sens = analogRead(sensorPin);
  if (sens > threshold) {     // bail out on sensor detect
    x = 0;
    break;
  }
  delay(50);
}

continue

It is simply used to skip an iteration based on certain condition. Skipping to next iteration

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for (int x = 0; x <= 255; x ++) {
  if (x > 40 && x < 120) {  // create jump in values
    continue;
  }

  analogWrite(PWMpin, x);
  delay(50);
}

while loop

it is a type of loop that will continuously execute until the condition inside the paranthesis is false.

Example

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var = 0;
while (var < 200) {
  // do something repetitive 200 times
  var++;
}

do…while loop

It is equivalent to while the loop except that the condition is executed at the end of the loop. This means that the loop will be executed at least once.

Example

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int x = 1;
do {
  delay(50);          // wait for sensors to stabilize
  x = readSensors();  // check the sensors
} while (x < 10);

if

If the statement checks the condition and executes the code inside curly braces, if the condition is true.

‘else’

else statement is executed whenever an if condition is false. It can be chained to form a bunch of if..else statements when there many conditions involved.

Example

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if (temperature >= 70) {
  // Danger! Shut down the system.
}
else if (temperature >= 60) { // 60 <= temperature < 70
  // Warning! User attention required.
}
else { // temperature < 60
  // Safe! Continue usual tasks.
}

for loop

The for statement is used to loop a sequence of code wrapped within curly braces.

Example

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// Dim an LED using a PWM pin
int PWMpin = 10;  // LED in series with 470 ohm resistor on pin 10

void setup() {
  // no setup needed
}

void loop() {
  for (int i = 0; i <= 255; i++) {
    analogWrite(PWMpin, i);
    delay(10);
  }
}

goto

Transfers a program flow to a defined point of the program.

Example

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for (byte r = 0; r < 255; r++) {
  for (byte g = 255; g > 0; g--) {
    for (byte b = 0; b < 255; b++) {
      if (analogRead(0) > 250) {
        goto bailout;
      }
      // more statements ...
    }
  }
}

bailout:
// more statements ...

return

End a function and if desired, return the value from the function

Example

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int checkSensor() {
  if (analogRead(0) > 400) {
    return 1;
  }
  else {
    return 0;
  }
}

switch case

Switch case controls the flow of programs by allowing programmers to define a particular code that must be executed in various conditions.

Example

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switch (var) {
  case 1:
    //do something when var equals 1
    break;
  case 2:
    //do something when var equals 2
    break;
  default:
    // if nothing else matches, do the default
    // default is optional
    break;
}