How to get font size of your system?

I don't believe psdavis is correct.  No GetDeviceCaps function will tell you the system font size.  One way to do it is to get a screen compatible display context using CreateDC.  Then get the system font using GetStockObject(SYSTEMFONT).  Load the font into the CDC using SelectObject.  Finally, you can use the GetTextMetrics call to determine any information you need, including the size.  Don't forget to free up everything correctly.

The settings you need are stored in the registry:

1. Fetch the current configuration profile, stored here:

HKLM\System\CurrentControlSet\IDConfigDB\CurrentConfig

The value you get there is something like '0001'.

2. Using this value, the display dpi settings are stored here:

HKLM\Config\[ccfg]\Display\Settings
// [ccfg] <-- contains the value from [1]

The value names are:
DPILogicalX, DPILogicalY and
DPIPhysicalX, DPIPhysicalY

But i believe that psdavis is right. The way he proposed should deliver correct values, and
it doesn't depend on the registry.
BTW: The dpi settings *do* contain the system font size - as they tell how to scale the fonts.

Thanks snoeg!

psdavis is correct. A complete version is:

CDC DispDC;
DispDC.CreateIC("DISPLAY", NULL, NULL, NULL);
int nLogDPIX = DispDC.GetDeviceCaps(LOGPIXELSX),
    nLogDPIY = DispDC.GetDeviceCaps(LOGPIXELSY);

// if (nLogDPIX == 96 && nLogDPIY == 96) // small fonts
// if (nLogDPIX == 120 && nLogDPIY == 120) // large fonts
// otherwise, custom font size

Well there's an easier way to get all font attributes

LOGFONT lf ;
GetObject( GetStockObject(SYSTEM_FONT), sizeof lf, &lf ) ;

*All* the font attributes are then in lf.

Sorry that was SDK, add casts and ::

psdavis was right. Snoegler's answer with registry works only for 95. For NT the entries are in different location. jstolan's answer may work, but I did not try it. Chensu, as always, makes it easier by providing a complete version. Thanks to you all.

PSDavis was right. Chensu, as always, makes it easier by providing complete solution. I did not try Jstolan's solution. Snoegler's solution works for 95. It means that you need to check for OS and then read different registry location based on OS. I used Chensu's solution and it works fine. Thanks to you all.