The String case change functions allow you to change the case of a String. They work just as their names imply.
toUpperCase() changes the whole string to upper case characters, and
toLowerCase() changes the whole String to lower case characters. Only the characters A to Z or a to z are affected.
There is no circuit for this example, though your Arduino must be connected to your computer via USB.
/* String Case changes Examples of how to change the case of a string created 27 July 2010 modified 2 Apr 2012 by Tom Igoe http://arduino.cc/en/Tutorial/StringCaseChanges This example code is in the public domain. */
For more detail: Arduino String Case Change Functions Code