Arduino String Comparison Operators Code

The String comparison operators, ==, !=,>, < ,>=, <= , and the functionsequals() and equalsIgoreCase() allow you to make alphabetic comparisons between Strings. They’re useful for sorting and alphabetizing, among other things.

Arduino String Comparison Operators

The operator == and the function equals() perform identically. It’s just a matter of which you prefer. So

if (stringOne.equals(stringTwo)) {

is identical to

if (stringOne ==stringTwo) {

The greater than and less than operators evaluate strings in alphabetical order, on the first character where the two differ. So, for example "a" < "b" and "1" < "2", but "999"> "1000" because 9 comes after 1.

Caution: String comparison operators can be confusing when you’re comparing numeric strings, because you’re used to thinking of them as numbers, not strings. If you have to compare numbers, compare them as ints, floats, or longs, and not as Strings.


There is no circuit for this example, though your Arduino must be connected to your computer via USB.

image developed using Fritzing. For more circuit examples, see the Fritzing project page


Comparing Strings

Examples of how to compare strings using the comparison operators

created 27 July 2010
modified 2 Apr 2012
by Tom Igoe

This example code is in the public domain.

String stringOne, stringTwo;

void setup() {
// Open serial communications and wait for port to open:
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only

[box color=”#985D00″ bg=”#FFF8CB” font=”verdana” fontsize=”14 ” radius=”20 ” border=”#985D12″ float=”right” head=”Major Components in Project” headbg=”#FFEB70″ headcolor=”#985D00″]

Hardware Required

  • Arduino Board


For more detail: Arduino String Comparison Operators Code

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