How to embed a file into an executable?

A portable way is to define a function like

typedef unsigned char Byte;

Byte const* pngFileData()
{
    static Byte const data =
    {
        // Byte data generated by a helper program.
    };
    return data;
}

Then all you have to do is to write a little helper program that reads the PNG file as binary and generates the C++ curly braces initializer text. Edit: @awoodland has pointed out in comment to the question, that ImageMagick has such a little helper program…

Of course, for a Windows-specific program, instead use the ordinary Windows resource scheme.

Cheers & hth.,