please give me a hand

i’m a newbie in arduino!!!

i dont understand all parts of melody example in environment.

i dont know what is the function of the programe below the line.

does anyone can help me???><

/* Melody

  • (cleft) 2005 D. Cuartielles for K3
  • This example uses a piezo speaker to play melodies. It sends
  • a square wave of the appropriate frequency to the piezo, generating
  • the corresponding tone.
  • The calculation of the tones is made following the mathematical
  • operation:
  • timeHigh = period / 2 = 1 / (2 * toneFrequency)
  • where the different tones are described as in the table:
  • note frequency period timeHigh
  • c 261 Hz 3830 1915
  • d 294 Hz 3400 1700
  • e 329 Hz 3038 1519
  • f 349 Hz 2864 1432
  • g 392 Hz 2550 1275
  • a 440 Hz 2272 1136
  • b 493 Hz 2028 1014
  • C 523 Hz 1912 956
  • http://www.arduino.cc/en/Tutorial/Melody
    */

int speakerPin = 9;

int length = 15; // the number of notes
char notes = "ccggaagffeeddc "; // a space represents a rest
int beats = { 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 4 };
int tempo = 300;

void playTone(int tone, int duration) {
for (long i = 0; i < duration * 1000L; i += tone * 2) {
digitalWrite(speakerPin, HIGH);
delayMicroseconds(tone);
digitalWrite(speakerPin, LOW);
delayMicroseconds(tone);
}
}

void playNote(char note, int duration) {
char names = { ‘c’, ‘d’, ‘e’, ‘f’, ‘g’, ‘a’, ‘b’, ‘C’ };
int tones = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 };

// play the tone corresponding to the note name
for (int i = 0; i < 8; i++) {
if (names == note) {
_ playTone(tones*, duration);_
_
}_
_
}_
_
}_
void setup() {
_
pinMode(speakerPin, OUTPUT);_
_
}_
void loop() {
_
for (int i = 0; i < length; i++) {_
_ if (notes == ’ ') {_
delay(beats _ tempo); // rest_

* } else {*
playNote(notes, beats * tempo);
* }*

* // pause between notes*
* delay(tempo / 2);*
* }*
}

You mean “playTone”?

It simply turns a digital pin on and off at a given rate for a given amount of time.

for (long i = 0; i < duration * 1000L; i += tone * 2) {
   digitalWrite(speakerPin, HIGH);
   delayMicroseconds(tone);
   digitalWrite(speakerPin, LOW);
   delayMicroseconds(tone);
 }

So, duration is in milliseconds (1/1000th of a second) and “tone” is specified in microseconds (1/1000th of a millisecond).
Since there are two delays per loop, it increments the loop counter “i” by twice the delay, and repeats the loop until “i” >= “duration * 1000”.