Arduino/build/shared/examples/08.Strings/StringToInt/StringToInt.ino

/*
  String to Integer conversion

  Reads a serial input string until it sees a newline, then converts the string
  to a number if the characters are digits.

  The circuit:
  - No external components needed.

  created 29 Nov 2010
  by Tom Igoe

  This example code is in the public domain.

  http://www.arduino.cc/en/Tutorial/StringToInt
*/

String inString = "";    // string to hold input

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  // send an intro:
  Serial.println("\n\nString toInt():");
  Serial.println();
}

void loop() {
  // Read serial input:
  while (Serial.available() > 0) {
    int inChar = Serial.read();
    if (isDigit(inChar)) {
      // convert the incoming byte to a char and add it to the string:
      inString += (char)inChar;
    }
    // if you get a newline, print the string, then the string's value:
    if (inChar == '\n') {
      Serial.print("Value:");
      Serial.println(inString.toInt());
      Serial.print("String: ");
      Serial.println(inString);
      // clear the string for new input:
      inString = "";
    }
  }
}