/* String length() Examples of how to use length() in a String. Open the Serial Monitor and start sending characters to see the results. created 1 Aug 2010 by Tom Igoe http://www.arduino.cc/en/Tutorial/StringLengthTrim This example code is in the public domain. */ String txtMsg = ""; // a string for incoming text int lastStringLength = txtMsg.length(); // previous length of the String 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 } // send an intro: Serial.println("\n\nString length():"); Serial.println(); } void loop() { // add any incoming characters to the String: while (Serial.available() > 0) { char inChar = Serial.read(); txtMsg += inChar; } // print the message and a notice if it's changed: if (txtMsg.length() != lastStringLength) { Serial.println(txtMsg); Serial.println(txtMsg.length()); // if the String's longer than 140 characters, complain: if (txtMsg.length() < 140) { Serial.println("That's a perfectly acceptable text message"); } else { Serial.println("That's too long for a text message."); } // note the length for next time through the loop: lastStringLength = txtMsg.length(); } }