const int led=10;
const int ldr=A0;
int data;

void setup() {
pinMode(led, OUTPUT);
pinMode(ldr, INPUT);
Serial.begin(9600);

}

void loop() {
int ldrvalue = analogRead(ldr);
ldrvalue = map(ldrvalue, 0,1023,255,0);
  float voltage = ldrvalue *(5.0/1023.0);
  Serial.print("ldr sensor data:");
  Serial.println(voltage);
  Serial.println("[v]");

  analogWrite(led, ldrvalue);
  delay(200);
}