How to Use Struct in Arduino: Simple Guide with Examples

In Arduino, use struct to group related variables under one name, making your code organized and easier to manage. Define a struct with the struct keyword, then create variables of that type to store multiple related values together.

Syntax

A struct groups different variables into one named type. You start with the struct keyword, give it a name, then list variables inside curly braces. After defining it, you can create variables of this new type.

• struct: keyword to define a structure
• Name: the name of your struct type
• Members: variables inside the struct, can be different types
• Variable: create a variable of the struct type to hold data

arduino

struct SensorData {
  int temperature;
  int humidity;
  bool isActive;
};

SensorData sensor1;  // variable of type SensorData

Example

This example shows how to define a struct for sensor data, assign values, and print them to the Serial Monitor.

arduino

#include <Arduino.h>

struct SensorData {
  int temperature;
  int humidity;
  bool isActive;
};

SensorData sensor1;

void setup() {
  Serial.begin(9600);
  sensor1.temperature = 25;
  sensor1.humidity = 60;
  sensor1.isActive = true;

  Serial.print("Temperature: ");
  Serial.println(sensor1.temperature);
  Serial.print("Humidity: ");
  Serial.println(sensor1.humidity);
  Serial.print("Active: ");
  Serial.println(sensor1.isActive ? "Yes" : "No");
}

void loop() {
  // Nothing here
}

Output

Temperature: 25
Humidity: 60
Active: Yes

Common Pitfalls

Common mistakes when using struct in Arduino include:

• Forgetting the semicolon ; after the struct definition.
• Not initializing struct variables before use, which can cause unexpected values.
• Confusing the struct type name with variable names.
• Trying to print a whole struct directly instead of its members.

arduino

/* Wrong: Missing semicolon after struct definition */
struct Data {
  int x;
  int y;
};  // <-- Missing semicolon was here

/* Right: */
struct Data {
  int x;
  int y;
};

Quick Reference

• Define a struct with struct Name { members };
• Create variables of that struct type to hold grouped data
• Access members with dot notation, e.g., variable.member
• Always end struct definitions with a semicolon
• Initialize members before use to avoid garbage values

Key Takeaways

Use struct to group related variables under one name for better organization.

Always end your struct definition with a semicolon.

Access struct members using dot notation like myStruct.member.

Initialize struct variables before using their values to avoid unexpected results.

You cannot print a whole struct directly; print each member separately.