// declares s1 with an initial string
String s1 = String("string number one"); 
byte bytes[20];  // array of byte. 
char array[20];  // array of char.

void setup() {
  Serial.begin(9600); 
  // turn ON wiring hardware LED
  pinMode(WLED, OUTPUT);  
  digitalWrite(WLED, HIGH);

  // s2 holds "10000"
  String s2 = String(10000);  
  Serial.println("s2 holds: " + s2);

  // s3 holds "567000"
  String s3 = String(567000, DEC); 
  Serial.println("s3 holds: " + s3);

  // s4 holds "string number four"
  String s4 = "string number four";  
  Serial.println("s4 holds: " + s4);

  // use + operator to add a string
  s4 += " plus another part";  
  // user + operator when printing to serial
  Serial.println("now s4 holds: " + s4);  

  // get character at position 5
  char c = s4.charAt(5);  
  Serial.print ("c holds: ");
  Serial.println(c);  // prints 'g'

  // s5 holds "string number one"
  String s5 = String("string number one");  

  int cmp = s1.compareTo(s5);  // compare s1 to s5
  if (cmp == 0) {
    Serial.println("s1 and s5 are equal");  // prints equal
  } 
  else {
    Serial.println("s1 and s5 are different");
  }

  // check if s5 ends with "one"
  if (s5.endsWith("one"))  
    // prints "s5 ends with "one""
    Serial.println("s5 ends with one");  

  if (s1.equals(s5))  // check if s1 equal to s5
      Serial.println("s1 and s5 are equal");  // prints equal

  // s6 holds "string NUMBER one"
  String s6 = String("string NUMBER one");  
  // check if s5 and s6 are equal ignoring case differences
  if (s5.equalsIgnoreCase(s6))  
    // prints equal
    Serial.println("s6 and s5 are equal ignoring the case");  

  Serial.print ("index of char R pn s6 is: ");
  Serial.println(s6.indexOf('R'), DEC);  // prints 12

  Serial.print ("index of char R on s6 from index 13 is: ");
  // prints -1, not found
  Serial.println(s6.indexOf('R', 13), DEC);  

  String s7 = s6.substring(7, 13);
  Serial.println("s7 is: "+s7);  // prints "NUMBER"

  Serial.print ("index of string NUMBER on s6 is: ");  
  Serial.println(s6.indexOf(s7), DEC);  // prints 7

  Serial.print ("last index of char 'n' on s6 is: ");  
  Serial.println(s6.lastIndexOf('n'), DEC);  // prints 15

  Serial.print ("length of s6 is: ");  
  Serial.println(s6.length(), DEC);  // prints 17

  // set character at index 15 to 'N'
  s6.setCharAt(15, 'N');  
  // prints "string NUMBER oNe"
  Serial.println("s6 is: "+s6);  

  // check if s6 starts with "string"
  if (s6.startsWith("string"))  
    // s6 starts with "string" string
    Serial.println("s6 starts with string"); 

  // prints "string number one"
  s6.toLowerCase();
  Serial.println("s6 to lower case is: "+s6);  

  // prints "STRING NUMBER ONE"
  s6.toUpperCase();
  Serial.println("s6 to upper case is: "+s6);  

  s6.concat(" plus spaces at the end   ");  // concat a string
  // prints "STRING NUMBER ONE plus spaces at the end   "
  Serial.println("s6 is: "+s6);  

  // prints "STRING NUMBER ONE plus spaces at the end" 
  s6.trim();
  Serial.println("trim of s6 is: "+s6); 

  // prints "STRING NUMBER ONE plus spac5s at th5 5nd"
  s6.replace('e', '5');
  Serial.println("s6 is: "+s6);  

  // get the byte array in the array byte.
  s6.getBytes(bytes, 20);  
  Serial.print ("array byte. is: ");
  for (int i=0; i<20; i++) {
    // prints "S T R I N G   N U M B E R   O N E   p"
    Serial.write(bytes[i]);
    Serial.print(" ");
  }
  Serial.println();
  Serial.print ("array array is: ");
  s6.toCharArray(array, 20);
  Serial.println(array);  // Prints "STRING NUMBER ONE p"
}

void loop() {

}