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This example is for Wiring version 1.0 build 0100+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.

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()
    {

    }