new to Ardunio but trying to compile

[code]
const int MIC = A0; //the microphone amplifier output is connected to pin A0
int adc;
int dB, PdB; //the variable that will hold the value read from the microphone each time

void setup() {
Serial.begin(9600); //sets the baud rate at 9600 so we can check the values the microphone is obtaining on the Serial Monitor
  pinMode(2, OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
}

void loop(){

  PdB = dB; //Store the previous of dB here
 
adc= analogRead(MIC); //Read the ADC value from amplifer
//Serial.println (adc);//Print ADC for initial calculation
dB = 20 * log10 (analogRead(MIC)/ 0.1); //Convert ADC value to dB using Regression values

if (PdB!=dB)
Serial.println (dB);

if (dB>70)

  digitalWrite(2, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(200);                       // wait for a second
  digitalWrite(2, LOW);

//delay(10);
if (dB<70)
digitalWrite(3,HIGH);
delay(200);
digitalWrite(3,LOW);
if (dB<60)
digitalWrite(4,HIGH);
delay(200);
digitalWrite(4,LOW);
}

[code]

const int SoundIn = A0;
void setup()
{
  Serial.begin(9600);
}
// put your setup code here, to run once:
void loop()
{
  int val = 20 * log10(analogRead(SoundIn)) / 0.1;

                       Serial.print(val);
                       Serial.println("db = ");
}

const int SoundIn = A0;


void setup() {
  // put your setup code here, to run once:

  Serial.begin(9600);
}


void loop() {
  // put your main code here, to run repeatedly:

  int ADCValue = (analogRead(SoundIn)) ;          //this line reads the ADC input into the variable ADCValue

  int dBValue = 20 * log10(ADCValue);                //this line calculates the dB level of ADCValue and puts it in the varialbe dBValue

  Serial.print("ADC count: ");                                //this line, with the "print" command prints the label "ADC count: " and leaves the cursor at the end of the line
  Serial.print(ADCValue);                                     //this line prints the value of ADCValue where the last line left off and leaves the cursor at the end of the line
  Serial.print("     dB level: ");                               //this line prints the label "    dB level: " and leaves the cursor at the end of the line
  Serial.println(dBValue);                                     //this line, withe the "println" command prints the value of dBValue at the end of the line, and moves the cursor to
                                                                            //the beginning of the next line for the next measurement

  delay(100);                                                        //this line delays for 0.1 second before the process repeats
}

//Code courtesy of Jon, to inch the process along

level = abs(adc_sample - 512);

//Serial.print("ADC count: ");                                //this line, with the "print" command prints the label "ADC count: " and leaves the cursor at the end of the line
  Serial.print(ADCValue);                                     //this line prints the value of ADCValue where the last line left off and leaves the cursor at the end of the line
 // Serial.print("     dB level: ");                               //this line prints the label "    dB level: " and leaves the cursor at the end of the line
//  Serial.println(dBValue);                                     //this line, withe the "println" command prints the value of dBValue at the end of the line, and moves the cursor to
                                                                            //the beginning of the next line for the next measurement