c++ compilation error (undefined reference)

[Baraclese]

Hi, I wrote a TGA header file and I wanted to test it with a small main 
file.
tga.h looks something like this:
class TGA
{
	public:
	
		TGA();
		TGA(char *filename);
		~TGA();
		
		bool load(char const *filename);
}

tga.cpp looks like this:

#include "tga.h"
using namespace std;

main()
{
	TGA image;
	
	cout << "Filename: ";
	cin >> image.filename;
	
	if (image.load(image.filename))
		cout << "File successfully read./n";
	return 0;
}

When compiling using gcc 3.2 I receive the following error message:

$ g++ -mno-cygwin -lstdc++ f:/projects/cpp/tga.cpp -o tga.exe
/cygdrive/c/WIN98/TEMP/cccSDKcK.o(.text+0x9f0):tga.cpp: undefined 
reference to `TGA::TGA()'

What's the problem here?

regards,
Baraclese