Character Classification.

Characters are typographic symbols such as A, d, and %. The character datatype, abbreviated as char, stores letters and symbols in the ascii format. Characters are distinguished from other symbols by putting them between single quotes ('P'). This example demonstrates the use of character classification and conversion commands.

char tab = '\t';    // tab character
char digit = '1';   // digit character
char upperA = 'A';  // upper case 'A'
char lowerA = 'a';  // lower case 'a'
char colon = ',';   // comma
char val;

void setup()
{
  Serial.begin(9600);
  val = toLowerCase(upperA);
  Serial.print(val);                        // prints 'a'
  Serial.print(" ");
  Serial.print(isAlphaNumeric(digit), DEC); // prints 1 (true)
  Serial.print(" ");
  Serial.print(isAlpha(upperA), DEC);       // prints 1 (true)
  Serial.print(" ");
  Serial.print(isAscii(upperA), DEC);       // prints 1 (true)
  Serial.print(" ");
  Serial.print(isWhitespace(tab), DEC);     // prints 1 (true)
  Serial.print(" ");
  Serial.print(isGraph(lowerA), DEC);       // prints 1 (true)
  Serial.print(" ");
  Serial.print(isLowerCase(lowerA), DEC);   // prints 1 (true)
  Serial.print(" ");
  Serial.print(isSpace(val), DEC);          // prints 0 (false)
  Serial.print(" ");
  Serial.print(isUpperCase(upperA), DEC);   // prints 1 (true)
  Serial.print(" ");
  Serial.print(isControl(upperA), DEC);     // prints 0 (false)
  Serial.print(" ");
  Serial.print(isDigit(digit), DEC);        // prints 1 (true)
  Serial.print(" ");
  Serial.print(isGraph(digit), DEC);        // prints 1 (true)
  Serial.print(" ");
  Serial.print(isPunct(colon), DEC);        // prints 1 (true)
  Serial.print(" ");
  Serial.print(isHexadecimalDigit('F'), DEC);  // prints 1 (true)
  Serial.print(" ");
  val = toLowerCase('K');                   // prints 'k'
  Serial.print(val);
  Serial.print(" ");
  val = toAscii(40);
  Serial.println(val);                      // prints '('
}

void loop()
{

}