code for ch. 4 in white book

const int GLED=9 ;
const int RLED= 11 ;
const int BLED= 10 ;
const int REDSENSOR= A0 ;
const int GREENSENSOR = A1 ;
const int BLUESENSOR = A2;

int REDValue = 0;
int GREENValue = 0;
int BLUEValue = 0;
int redsensorValue = 0;
int greensensorValue = 0;
int bluesensorValue= 0;

void setup ()
{
  Serial.begin(9600);
  pinMode(REDSENSOR, INPUT) ;
  pinMode(GREENSENSOR, INPUT) ;
  pinMode(BLUESENSOR, INPUT) ;
  pinMode(GLED, OUTPUT) ;
  pinMode(RLED, OUTPUT) ;
  pinMode(BLED, OUTPUT) ;
}

void loop ()
{
  redsensorValue = analogRead(REDSENSOR);
  delay (50) ;
  greensensorValue = analogRead(GREENSENSOR) ;
  delay (50) ;
  bluesensorValue = analogRead(BLUESENSOR) ;
  delay (50) ;
  Serial.print("Raw Sensor Values \t Red: ");
  Serial.print(redsensorValue);
  Serial.print("\t Green: ");
  Serial.print(greensensorValue);
  Serial.print("\t Blue: ");
  Serial.println(bluesensorValue);
  REDValue = map(redsensorValue,550, 900, 255, 0);
  REDValue = constrain(REDValue, 0, 255) ;
  GREENValue = map(greensensorValue,650,900, 255, 0);
  GREENValue = constrain(GREENValue, 0, 255);
  BLUEValue = map(bluesensorValue,400, 800, 255, 0);
  BLUEValue = constrain(BLUEValue, 0, 255) ;

  Serial.print("Mapped Sensor Values \t Red: ");
  Serial.print(REDValue);
  Serial.print("\t Green: ");
  Serial.print(GREENValue);
  Serial.print("\t Blue: ");
  Serial.println(BLUEValue);
  delay(50) ;
  analogWrite(RLED, REDValue) ;
  analogWrite(GLED, GREENValue);
  analogWrite(BLED, BLUEValue);
}