Arduino Basic Tutorial

Arduino String Concatenation with Examples

Understanding Arduino String Concatenation

Arduino is a popular platform for creating interactive projects, and one of the most common tasks in programming Arduino is manipulating strings. String concatenation is the process of combining multiple strings into a single string. In this article, we will explore the concept of Arduino string concatenation and provide examples to help you understand how to use it effectively in your projects.

Arduino string concatenation

Why Use String Concatenation in Arduino?

String concatenation is a powerful tool that allows you to create dynamic strings by combining different pieces of text. This can be particularly useful in Arduino projects where you need to display or transmit data in a specific format. By concatenating strings, you can easily build complex messages or format data for output.

How to Concatenate Strings in Arduino

There are several ways to concatenate strings in Arduino, depending on your specific requirements. Here are three common methods:

Method 1: Using the + Operator

The simplest way to concatenate strings in Arduino is by using the + operator. This operator works similarly to addition but instead of adding numbers, it concatenates strings. Here is example:

In this example, we define two strings, “firstName” and “lastName”, and then concatenate them using the + operator. The resulting string “fullName” will contain the value “Fawad Khan”.

Method 2: Using the concat() Function

Arduino also provides a built-in function called “concat()” that you can use to concatenate strings. This function takes one or more arguments and returns a new string that is the concatenation of all the input strings. Here is example:

In this example ¬†we start with the string “Hello” and then use the “concat()” function to append the string ” World” to it. The resulting string, “message”, will contain the value “Hello World”.

Method 3: Using the strcat() Function

If you are familiar with the C programming language, you may already be familiar with the “strcat()” function. Arduino also provides a similar function that you can use to concatenate strings. Here is example:

In this example, we define two character arrays, “greeting” and “name”, and then use the “strcat()” function to concatenate the contents of “name” to the end of “greeting”. The resulting array, “greeting”, will contain the value “Hello World”.

Best Practices for String Concatenation in Arduino

While string concatenation can be a powerful tool, it’s important to use it judiciously to avoid performance issues or memory limitations. Here are some best practices to keep in mind:

Use the String Class Sparingly

The Arduino String class provides a convenient way to work with strings, but it can also consume a significant amount of memory. If you are concatenating strings frequently or dealing with large amounts of data, consider using character arrays instead.

Preallocate Memory for Concatenation

When concatenating strings, it is important to allocate enough memory to hold the resulting string. If you do not preallocate enough memory, your program may crash or produce unexpected results. Make sure to account for the maximum possible length of the concatenated string.

Avoid Excessive String Concatenation

String concatenation can be a slow operation, especially when working with large strings. If possible, try to minimize the number of concatenations in your code and consider alternative approaches, such as using string formatting or prebuilt strings.


Arduino string concatenation is a useful technique for combining multiple strings into a single string. By understanding the different methods available and following best practices, you can effectively manipulate strings in your Arduino projects. Whether you are building a display, transmitting data, or formatting output, string concatenation can help you achieve your desired results.

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