For calibrating a line follower bot, which uses three IR sensors.

calibration.ino

int sensorPin[]={A0,A1,A2};     /*Array of analog pins for sensor*/ 
int totalpin=3;                 /*Total No. of pins*/  
const int ledpin=9;       
int sensorMin[]={1023,1023,1023};  /*Array to store minimum values*/
int sensorMax[]={0,0,0};           /*Array to store maximum values*/
float sensorAvg[]={0.0,0.0,0.0};   /*Array to store average values*/

void calib()
{
  int i,l,temp;
  for(l=0;l<1000;l++)
  {
    for(i=0;i<totalpin;i++)
    {
      temp=analogRead(sensorPin[i]);     /*Read the value from sensor*/
      if(temp>sensorMax[i])              /*Find the maximum value*/
      {
        sensorMax[i]=temp;
      }
      if(temp<sensorMin[i])               /*Find the minimum value*/
      {
        sensorMin[i]=temp;
      }
    }
    delay(10);
  }
  for(i=0;i<totalpin;i++)
  {
    sensorAvg[i]=(sensorMax[i]+sensorMin[i])/2;   /*Find the average value*/
  }
}

void setup()
{
  Serial.begin(9600);
  int i;
  for(i=0;i<totalpin;i++)
  {
    pinMode(sensorPin[i],INPUT);    /*To declare analog pins to input mode*/
  }
  
  calib();                    /* call function for calibration*/
}

int a,b,c,x,y,z;
void loop()
{
  a=analogRead(sensorPin[0]);
  if(a<sensorAvg[0])
  {
    Serial.print("black");
    x=0;                             /*x=0 on black surface for sensor connected to A0 */
  }
  else
  {
    Serial.print("White");
    x=1;                             /*x=1 on white surface for sensor connected to A0*/
  }
  Serial.print(" ");
  
  b=analogRead(sensorPin[1]);
  if(b<sensorAvg[1])
  {
    Serial.print("black");         
    y=0;                              /*y=0 on black surface for sensor connected to A1*/
  }
  else
  {
    Serial.print("white");
    y=1;                                 /*y=1 on white surface for sensor connected to A1*/
  }
  Serial.print(" ");
  
  c=analogRead(sensorPin[2]);
  if(c>sensorAvg[2])
  {
    Serial.print("white");
    z=1;                               /*z=1 on white surface for sensor connected to A2*/
  }
  else
  {
    Serial.print("black");
    z=0;                               /*z=0 on black surface for sensor connected to A2*/
  }
  Serial.print(" ");
  
  Serial.print("\n");
  if(x==0 && y==1 && z==0)
  {
  //Go Straight
  }

  if(x==1&&y==0&&z==0)
  {
  //Turn Left
  }

  if(x==0&&y==0&&z==1)
  {
  //Turn Right
  }

  if(x==1&&y==1&&z==0)
  {
  //Turn Left
  }
  
  if(x==0&&y==1&&z==1)
  {
  //Turn Right
  }
}