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compareTo()This tutorial will discuss comparing two strings using the function in Arduino .

compareTo()Comparing strings using the Arduino function

To compare two strings in Arduino, we can use compareTo()the function of the string object. compareTo()The function compares the characters present in both the strings one by one to find out whether the two strings are the same.

compareTo()The function starts at the first character of both strings and compares them using their ASCII values, if the strings match it moves on to the next character. Each keyboard character has a unique ASCII value.

The ASCII values ​​of uppercase and lowercase letters are different; athe ASCII value of is 97 and Athe value of is 65. If we want to compare two strings ignoring case, we must ensure that both strings are either uppercase or lowercase.

To convert a string to uppercase, we can use the function of the string object in Arduino toUpperCase(). To convert a string to lowercase, we can use toLowerCase()the function of the string object in Arduino.

If the two strings are equal, compareTo()the function returns 0. If the ASCII value of the first string is less than the ASCII value of the second string, compareTo()the function returns a negative number.

If the ASCII value of the first string is greater than the ASCII value of the second string, the function returns a positive number. For example, let's define two string variables and compare them compareTo()using the function in Arduino .compareTo()

String string_1 = "Hello";
String string_2 = "World";
int result = 0;

void setup() { result = string_1.compareTo(string_2); }
void loop() {}

The result of the comparison will be stored resultin the variable. We can also use equals()the function instead of compareTo()the function.

equals()Comparing strings using the Arduino function

equals()The function returns a boolean value, true if the two strings are equal, false otherwise. equals()The function is also case sensitive, which means that abcwill not be equal ABC.

equals()Check out this link for more details about the compare function. If we want to compare two strings ignoring case sensitivity, we can use the compare equalsIgnoreCase()function of the string object.

equalsIgnoreCase()also returns a boolean value which is case insensitive, meaning abcand ABCwill be equal and the function will return true. Check this link for equalsIgnoreCase()more details on the function.

Comparing Strings Using Comparison Operators in Arduino

We can also use comparison operators such as less than or equal to <=, greater than or >=equal to, equal ==to to compare strings.

In this case, the strings are compared based on the ASCII values ​​of the characters present in them, which means that the comparison will also be case-sensitive.

For example, the following statement will return false.

"hello" == "Hello"