Can't create basic class

Hey guys, I've been searching for help on this for hours and can't find it. Created a file SonarSensor.h:

#ifndef SonarSensor
#define SonarSensor
#include <WProgram.h>

//SonarSensor.h: a class to abstract the sonar sensors, since there will be multiple.
class SonarSensor
{
 public:
  SonarSensor(int digitalPin, int analogOutputPin);
  int getRawReading();
  int getScaledReading();
 private:
  void pulse();

  float scaleFactor;
  int RXpin, int ANpin;  //digital control and analog output, respectively
};

#endif

and SonarSensor.cpp:

#include <WProgram.h>
#include "SonarSensor.h"
//SonarSensor.cpp: a class to abstract the sonar sensors, since there will be multiple.

  void SonarSensor::pulse()
  {
    //pulse sonar
    digitalWrite(RXpin, LOW);
    digitalWrite(RXpin, HIGH);
    delay(5);
    digitalWrite(RXpin, LOW);
  }
  
  SonarSensor::SonarSensor(int digitalPin, int analogOutputPin)
  {
    scaleFactor = 0.5f;  //can't initalize otherwise
    RXpin = digitalPin;
    ANpin = analogOutputPin;
    pinMode(RXpin, OUTPUT);
    pinMode(ANpin, INPUT);
  }
  
  //returns raw sonar value, only useful for debugging
  int SonarSensor::getRawReading()
  {
    pulse();
    return analogRead(ANpin);
  }
  
  //returns the sonar value in inches
  int SonarSensor::getScaledReading()
  {
    return getRawReading() * scaleFactor;
  }

put them in a folder, put them in a library, and tried creating a file to test it:

#include "SonarSensor.h"

void setup()
{}

void loop()
{}

here are the errors I'm getting:

C:\Documents and Settings\acm\Desktop\arduino-0017\hardware\libraries\SonarSensor\/SonarSensor.h:9: error: expected unqualified-id before 'int'

C:\Documents and Settings\acm\Desktop\arduino-0017\hardware\libraries\SonarSensor\/SonarSensor.h:9: error: expected `)' before 'int'

C:\Documents and Settings\acm\Desktop\arduino-0017\hardware\libraries\SonarSensor\/SonarSensor.h:16: error: expected unqualified-id before 'int'
..(and more)

I have no idea what the heck "expected unqualified-id before 'int'" means. using Arduino 0018 alpha on Windows XP. Please help!

Change...

#ifndef SonarSensor
#define SonarSensor

...to...

#ifndef SonarSensor_h
#define SonarSensor_h