how can I write the program abt 3 channels ??

int P1 = 9;
int P2 = 10;
int P3 = 11;

int length = 4; // the number of notes
char notes[] = "CDEF"; // a space represents a rest
int beats[] = { 1, 1, 1, 1 } ;
int tempo = 300;

void playTone(int tone, int duration) {
for (long i = 0; i < duration * 1000L; i += tone * 2)
if (tone > 1500 ){
digitalWrite(P1, HIGH);
digitalWrite(P2, LOW);
digitalWrite(P3, LOW);}
if (tone < 1500, tone > 1100 ){
digitalWrite(P1, LOW);
digitalWrite(P2, HIGH);
digitalWrite(P3, LOW);}
else{
delayMicroseconds(tone);
digitalWrite(P1, LOW);
digitalWrite(P2, LOW);
digitalWrite(P3, HIGH);
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(P1, OUTPUT);_
_
pinMode(P2, OUTPUT);_
_
pinMode(P3, 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);*
* }*
}
1. Can I write this to be a 3 channels PIANO?
2. the function 'CHAR' only can carry 1 character?
3. the timehigh range from XX to XX ....??
plz give me a hand>< thx all the brothers...

Please post code using the hash icon in the reply box.

Can I write this to be a 3 channels PIANO?

If you mean make the arduino sound like a piano then no it won't do this.

This program method will only play one note at a time.
For polyphonic programming see:-
http://www.arduino.cc/playground/Main/InterfacingWithHardware#Audio