robot that should turn left on its own and keep itself going strait

Using Arduino Programming Questions
10

Humans are really bad at repetition; computers are really good at it.

void forward()
{
  moveMotor (0, 0x7F);
  moveMotor (2, 0x7E);
}

void rightWall(int duration)
{
  moveMotor (0, 0x40);
  moveMotor (2, 0x7D);
}

void leftWall(int duration)
{
  moveMotor (0, 0x7F);
  moveMotor (2, 0x7D);
}

void reverse(int duration)
{
  moveMotor (1, 0x45);
  moveMotor (3, 0x45);
}

void leftTurn(int duration)
{
  moveMotor (0, 0x45);
  moveMotor (2, 0x7D);
}

void rightTurn(int duration)
{
  moveMotor (0, 0x7F);
  moveMotor (2, 0x45);
}

void moveMotor (unsigned char motor, unsigned char speed)
{
  unsigned char buff[4];
  //left motor
  buff[0]=0x80;
  buff[1]=0x00;
  buff[2]=motor;
  buff[3]=speed;
  for(int i=0; i<4; i++) {
    Serial.print(buff[i], BYTE);
  }
}

Reducing source size gives bugs fewer dusty corners to hide in.