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/*
Comparing Strings
Examples of how to compare strings using the comparison operators
created 27 July 2010
modified 2 Apr 2012
by Tom Igoe
http://arduino.cc/en/Tutorial/StringComparisonOperators
This example code is in the public domain.
*/
String stringOne, stringTwo;
void setup() {
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
stringOne = String("this");
stringTwo = String("that");
// send an intro:
Serial.println("\n\nComparing Strings:");
Serial.println();
}
void loop() {
// two strings equal:
if (stringOne == "this") {
Serial.println("StringOne == \"this\"");
}
// two strings not equal:
if (stringOne != stringTwo) {
Serial.println(stringOne + " =! " + stringTwo);
}
// two strings not equal (case sensitivity matters):
stringOne = "This";
stringTwo = "this";
if (stringOne != stringTwo) {
Serial.println(stringOne + " =! " + stringTwo);
}
// you can also use equals() to see if two strings are the same:
if (stringOne.equals(stringTwo)) {
Serial.println(stringOne + " equals " + stringTwo);
}
else {
Serial.println(stringOne + " does not equal " + stringTwo);
}
// or perhaps you want to ignore case:
if (stringOne.equalsIgnoreCase(stringTwo)) {
Serial.println(stringOne + " equals (ignoring case) " + stringTwo);
}
else {
Serial.println(stringOne + " does not equal (ignoring case) " + stringTwo);
}
// a numeric string compared to the number it represents:
stringOne = "1";
int numberOne = 1;
if (stringOne.toInt() == numberOne) {
Serial.println(stringOne + " = " + numberOne);
}
// two numeric strings compared:
stringOne = "2";
stringTwo = "1";
if (stringOne >= stringTwo) {
Serial.println(stringOne + " >= " + stringTwo);
}
// comparison operators can be used to compare strings for alphabetic sorting too:
stringOne = String("Brown");
if (stringOne < "Charles") {
Serial.println(stringOne + " < Charles");
}
if (stringOne > "Adams") {
Serial.println(stringOne + " > Adams");
}
if (stringOne <= "Browne") {
Serial.println(stringOne + " <= Browne");
}
if (stringOne >= "Brow") {
Serial.println(stringOne + " >= Brow");
}
// the compareTo() operator also allows you to compare strings
// it evaluates on the first character that's different.
// if the first character of the string you're comparing to
// comes first in alphanumeric order, then compareTo() is greater than 0:
stringOne = "Cucumber";
stringTwo = "Cucuracha";
if (stringOne.compareTo(stringTwo) < 0 ) {
Serial.println(stringOne + " comes before " + stringTwo);
}
else {
Serial.println(stringOne + " comes after " + stringTwo);
}
delay(10000); // because the next part is a loop:
// compareTo() is handy when you've got strings with numbers in them too:
while (true) {
stringOne = "Sensor: ";
stringTwo= "Sensor: ";
stringOne += analogRead(A0);
stringTwo += analogRead(A5);
if (stringOne.compareTo(stringTwo) < 0 ) {
Serial.println(stringOne + " comes before " + stringTwo);
}
else {
Serial.println(stringOne + " comes after " + stringTwo);
}
}
}
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