Arduino String

Arduino String
Arduino String

Arduino String is a single-board microcontroller used in many applications and products to make them more accessible. It aims to make system or application control interactive, creative, and effective. This software was inspired by the Wiring Platform and designed to be user-friendly and easy to understand for beginners. Strings can store values like ‘Hello’ or sensor values like ‘456’. Strings are usually implemented as arrays of bytes that store a succession of characters.

Each array element is identified by a number called an index. All strings use the null character, which is ‘0’ in numeric form and ‘NUL’ or ‘nul’ in ASCII. The Arduino programming language’s String class, Wiring API string class, or array of characters can be used to define a string. Strings are used in Arduino programming language to store character data like sensor readings. It includes the string library for string manipulation, the stringBuffer libraries for processing, and the Wiring libraries’ string class. This work investigated the

String data type’s capabilities and showed how it may be used in Arduino programming language tasks and exercises. It also provides instructions for using the work and manipulating strings. Finally, the String vs. character array data type experiment and comparison was done. This study examined how the Compiler allocates memory for these two works. Both data types were tested for how long it took to perform simple and complicated manipulations.


Arduino strings are String objects. A string is a succession of characters kept as a single unit. Text is stored in strings. Alphanumeric characters can be used to form char arrays. Arduino strings are character groups. String declaration and definition must be done outside of setup and loop functions, which influence Arduino device behavior. String objects let you manage textual data; the Arduino string object provides member procedures to manipulate strings and acquire key string information. Many member functions return crucial string information as well as enable the string object to accomplish something. The amount of characters in the string or whether it comprises a specified set of characters is crucial information.

The only thing between /* and */ in C programming is a comment. If the string is null or has zero length, IsNullOrEmpty returns true; otherwise, it returns false. However, IsNullOrWhiteSpace examines if the string is null, has zero length, or contains only white-space characters like space, /t, /n, /r, and other special characters. If these conditions are met, this function returns true; otherwise, it returns false. Since char arrays have individual slots for each character, this is not true. Character arrays get the beginning and the number of bytes needed for the definition. The default character array syntax is char myString[numChars];

Arduino String Objects: An Introduction

Want to modify text and strings in Arduino sketches? String objects are ideal for storing and manipulating text strings on Arduino.

Making String Objects
You can generate a String object several ways:

String myString = “Hello”; //Using a string literal String myString = String(‘a’); //Using a character String myString = String(15); //Using a number

An String() without arguments creates an empty string.

String concatenation

Put two strings together with +:

String firstName = “John”; String lastName = “Doe”; String fullName = firstName + ” ” + lastName; // fullName is “John Doe”

Concat() is another option:

FullName = firstName.concat(” “).concat(lastName);

Length of String
Use length() to retrieve a string’s character count:

String “Hello World”; int stringLength = myString.length(); // 11

Finding String Characters
Use indexOf() to check if a string contains a character or substring:

String myString = “Hello World”; int firstO = myString.indexOf(‘o’); // firstO is 4, the index of the first o; int firstSpace = myString.indexOf(‘ ‘); // firstSpace is 5.

LastIndexOf() finds the last character instance:

myString.lastIndexOf(‘o’); // lastO is 7

Substring extraction

Substring() extracts substrings from strings:

String myString = “Hello World”; String subString = myString.substring(6, 11); // “World”

First, the start index, then the end index.

Replace Characters
Replace all instances of a character in a string with replace():

MyString = “Hello World”;
Replace ‘o’ with ‘x’ to make myString “Hellx Wxrld”

Case conversion

You can quickly capitalize, lowercase, or uppercase a string using:

toLowerCase(); toCapitalize(); // Capitalizes first word letter

Hope this helps you learn Arduino string manipulation! Any questions? Let me know.

Useful String manipulation methods
To receive data from Arduino, you’ll commonly edit strings. Luckily, the String class has several helpful methods.


The + operator concatenates strings. As an example:

The “Doe” string
String fullName = firstName+lastName;
FullName is “John Doe”


The length() method returns a string’s character count. As an example:

int messageLength = message.length();
Now msgLength 5


Using bracket notation and the character index, you can access individual string characters. As an example:

character firstLetter = word[0];
The initial letter is ‘A’
FourthLetter = word[3];
The fourth letter is ‘u’


Use substring() to extract a string. Use index to start and finish substrings. As an example:

String subMessage = message.substring(6, 11);
“World” is subMessage


Replace all instances of a character or substring in a string with.replace(). As an example:

Replace “o” with “x” in message.
New message: “Hellx Wxrld!”

You may easily manipulate strings in Arduino programs with these approaches. Have more questions? Let me know!

String Concatenation, Comparison, and Modification

Converting Cases

Add two strings in Arduino using the + operator. As an example:

LastName = “Smith”;
FullName = firstName + ” ” + lastName;
The entire name is “John Smith”

Concat() is another option:
String fullName = firstName.concat(” “).concat(lastName);
The entire name is “John Smith”
String Comparison
Equals() compares strings for equality:
If (firstName == lastName) {
// Never true.

You can also use == to compare string memory locations, not values:
If (firstName == lastName) {
This will never happen.

Compare strings alphabetically with compareTo():
If (firstName.compareTo(lastName) < 0) {
FirstName is less than LastName
Otherwise, if firstName.compareTo(lastName) > 0, {
firstName exceeds lastName
} else {
// firstName=lastName
String editing
Arduino string modification has numerous methods. Use length() to retrieve string length:
Int len = firstName.length(); // 4

Use charAt() to extract characters at an index:
FirstChar = firstName.charAt(0); firstChar = ‘J’

Use replace() to replace all character occurrences:
String name = “Smith”;
replace(‘i’, ‘y’);
“Smyth” is the name.

Use substring() to retrieve string parts:

String initial = firstName.substring(0, 1); // “J”

To uppercase or lowercase a string, use toUpperCase() or toLowerCase():
String upperName = name.toUpperCase(); “SMYTH”
String lowerName = name.toLowerCase(); “smyth”

These simple methods let you concatenate, compare, and alter strings quickly! Any questions? Let me know.
Arduino String Storage: Efficiency
An Arduino String Object Use
Arduino sketches may store and modify strings using the String object. This creates a String.

String myString = “Hello”;

This produces a “Hello” String object called myString. You can then invoke String object methods like:

MyString.length() returns 5
“HELLO” is returned by myString.toUpperCase().
MyString.substring(0, 3); // Returns “Hel”

Although convenient, String uses a lot of memory. No problem if you’re utilizing a few short Strings. However, larger projects with numerous Strings may have memory concerns.
Use Character Arrays
Character arrays save memory while storing strings. Define a character array:

char myString[6] = “Hello”;

The array of 6 characters (which holds “Hello” plus a null terminator) is initialized to “Hello”. Use to get string length:

This code returns 5 by subtracting 1 from the size of myString.

Perform operations like:

“Hi” is copied into myString using strcpy().
To add “there!” to myString, use the strcat function.
// Compare myString to “Hello” using strcmp.

Display Control

LCD displays need strings to show messages. Parsing strings to format text for display is common. Due to character limits, you may need to extract part of a string to show. You may need to merge many strings into one message. String parsing lets you customize text.
Information extraction
You may need to extract data from a string in numerous situations. For instance, a GPS module may send “lat=37.3847, lon=-122.0816”. This string can be parsed to get latitude and longitude coordinates as float variables for your code.

String parsing gives Arduino projects several options. After some practice, you’ll be confident manipulating strings to enable advanced drawing features. These examples are just the beginning—string parsing is a valuable Arduino ability.


So now you can manipulate strings in Arduino sketches like a pro with a few simple routines. The Arduino String library lets you compare strings, search for substrings, convert strings to various data types, concatenate, and format strings. This article’s reference charts help you choose the proper string function for any task. Get out there and string those characters to make your next Arduino project say what you want! Arduino string manipulation is easy with the String library.

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