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Conditional Statements and Loops

This lesson will introduce you to more programming structures which are essential to learn about.

Conditional statements​

Conditional statements allow us to perform different actions depending on whether a specific condition is true or false (a Boolean value). They allow our projects to involve decision-making and follow different paths of execution depending on a condition. For example, we can use conditional statements to turn an LED off if it's dark. We'll explore this later when we learn about the LDR.

There are a few main types of conditional statements we can use.

if statements​

if statements are used to execute some code if a certain condition is true:

if (condition) {
    // Do something
}

if...else statements​

if...else statements allow us to execute an alternate block of code if a condition is false:

if (condition) {
    // Do something
} else {
    // Do something else
}

if...else...if statements​

if...else...if statements allow us to check through multiple conditions.

if (condition1) {
    // Do something
} else if (condition2) {
    // Do something else
} else {
    // Do something else if both condition1 and condition2 are false
}

Loops​

Loops can be used to execute certain blocks of code multiple times. Each cycle of a loop is known as an iteration.

for loops​

A for loop is used when the number of iterations are known. This makes a for loop a count-controlled loop, since it will execute a block of code for a specific number of times.

for (initialization; condition; increment) {
      // statement(s);
}

for (int i = 0; i < 10; i++) {
    // Do something 10 times
}
Example

Blink an LED 5 times.

for (int i = 0; i < 5; i++) {
  digitalWrite(2, HIGH);
  delay(300);
  digitalWrite(2, LOW);
  delay(300);
}

while loops​

A while loop is a pre-condition loop. This means it checks for a condition before iterating, and the number of iterations is unknown beforehand.

while (condition) {
    // Do something
}
tip

Be careful! If the condition being checked is always true, the loop will run forever. For example:

int blink = 1;

while (blink == 1) {
  digitalWrite(2, HIGH);
  delay(500);
  digitalWrite(2, LOW);
  delay(500);
}

Assignment​

Your Turn
  1. Read this article to familiarse yourself with using conditional statements.
  2. Watch this video to understand loops better.

Next Steps​

This section includes links to help you dive deeper into the topics from this lesson. It's optional, so don't worry if you choose to skip it.