If Statement (Conditional Statement)

Use an if statement to change the output conditions based on changing the input conditions.

The if() statement is the most basic of all programming control structures. It allows you to make something happen or not, depending on whether a given condition is true or not. It looks like this:

1if (someCondition) {
2// do stuff if the condition is true

There is a common variation called if-else that looks like this:

1if (someCondition) {
2// do stuff if the condition is true
3} else {
4// do stuff if the condition is false

There's also the else-if, where you can check a second condition if the first is false:

1if (someCondition) {
2// do stuff if the condition is true
3} else if (anotherCondition) {
4// do stuff only if the first condition is false
5// and the second condition is true

You'll use if statements all the time. The example below turns on an LED on pin 13 (the built-in LED on many Arduino boards) if the value read on an analog input goes above a certain threshold.

Hardware Required

  • Arduino Board

  • Potentiometer or variable resistor






In the code below, a variable called

is used to store the data collected from a potentiometer connected to the board on analogPin 0. This data is then compared to a threshold value. If the analog value is found to be above the set threshold the built-in LED connected to digital pin 13 is turned on. If analogValue is found to be
(less than) threshold, the LED remains off.

Learn more

You can find more basic tutorials in the built-in examples section.

You can also explore the language reference, a detailed collection of the Arduino programming language.

Last revision 2015/07/29 by SM

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