Ok so I've read a book on C++ and whatnot, but it didn't really say what a struct was, it just mentioned that it was a cousin of a class and some other stuff. Now that I am reading Petzold's book, which uses C not C++ I've stumbled upon the following header file..............

Code:
struct
{
     int     iIndex ;
     TCHAR * szLabel ;
     TCHAR * szDesc ;
}
sysmetrics [] =
{
     SM_CXSCREEN,             TEXT ("SM_CXSCREEN"),              
                              TEXT ("Screen width in pixels"),
     SM_CYSCREEN,             TEXT ("SM_CYSCREEN"),              
                              TEXT ("Screen height in pixels"),
     SM_CXVSCROLL,            TEXT ("SM_CXVSCROLL"),             
                              TEXT ("Vertical scroll width"),
     SM_CYHSCROLL,            TEXT ("SM_CYHSCROLL"),             
                              TEXT ("Horizontal scroll height"),
     SM_CYCAPTION,            TEXT ("SM_CYCAPTION"),             
                              TEXT ("Caption bar height"),
     SM_CXBORDER,             TEXT ("SM_CXBORDER"),              
                              TEXT ("Window border width"),
     SM_CYBORDER,             TEXT ("SM_CYBORDER"),              
                              TEXT ("Window border height"),
     SM_CXFIXEDFRAME,         TEXT ("SM_CXFIXEDFRAME"),          
                              TEXT ("Dialog window frame width"),
     SM_CYFIXEDFRAME,         TEXT ("SM_CYFIXEDFRAME"),          
                              TEXT ("Dialog window frame height"),
     SM_CYVTHUMB,             TEXT ("SM_CYVTHUMB"),              
                              TEXT ("Vertical scroll thumb height"),
     SM_CXHTHUMB,             TEXT ("SM_CXHTHUMB"),              
                              TEXT ("Horizontal scroll thumb width"),
     SM_CXICON,               TEXT ("SM_CXICON"),                
                              TEXT ("Icon width"),
     SM_CYICON,               TEXT ("SM_CYICON"),                
                              TEXT ("Icon height"),
     SM_CXCURSOR,             TEXT ("SM_CXCURSOR"),              
                              TEXT ("Cursor width"),
     SM_CYCURSOR,             TEXT ("SM_CYCURSOR"),              
                              TEXT ("Cursor height"),
     SM_CYMENU,               TEXT ("SM_CYMENU"),                
                              TEXT ("Menu bar height"),
     SM_CXFULLSCREEN,         TEXT ("SM_CXFULLSCREEN"),          
                              TEXT ("Full screen client area width"),
     SM_CYFULLSCREEN,         TEXT ("SM_CYFULLSCREEN"),          
                              TEXT ("Full screen client area height"),
     SM_CYKANJIWINDOW,        TEXT ("SM_CYKANJIWINDOW"),         
                              TEXT ("Kanji window height"),
     SM_MOUSEPRESENT,         TEXT ("SM_MOUSEPRESENT"),          
                              TEXT ("Mouse present flag"),
     SM_CYVSCROLL,            TEXT ("SM_CYVSCROLL"),             
                              TEXT ("Vertical scroll arrow height"),
     SM_CXHSCROLL,            TEXT ("SM_CXHSCROLL"),             
                              TEXT ("Horizontal scroll arrow width"),
     SM_DEBUG,                TEXT ("SM_DEBUG"),                 
                              TEXT ("Debug version flag"),
     SM_SWAPBUTTON,           TEXT ("SM_SWAPBUTTON"),            
                              TEXT ("Mouse buttons swapped flag"),
     SM_CXMIN,                TEXT ("SM_CXMIN"),                 
                              TEXT ("Minimum window width"),
     SM_CYMIN,                TEXT ("SM_CYMIN"),                 
                              TEXT ("Minimum window height"),
     SM_CXSIZE,               TEXT ("SM_CXSIZE"),                
                              TEXT ("Min/Max/Close button width"),
     SM_CYSIZE,               TEXT ("SM_CYSIZE"),                
                              TEXT ("Min/Max/Close button height"),
     SM_CXSIZEFRAME,          TEXT ("SM_CXSIZEFRAME"),           
                              TEXT ("Window sizing frame width"),
     SM_CYSIZEFRAME,          TEXT ("SM_CYSIZEFRAME"),           
                              TEXT ("Window sizing frame height"),
     SM_CXMINTRACK,           TEXT ("SM_CXMINTRACK"),            
                              TEXT ("Minimum window tracking width"),
     SM_CYMINTRACK,           TEXT ("SM_CYMINTRACK"),            
                              TEXT ("Minimum window tracking height"),
     SM_CXDOUBLECLK,          TEXT ("SM_CXDOUBLECLK"),           
                              TEXT ("Double click x tolerance"),
     SM_CYDOUBLECLK,          TEXT ("SM_CYDOUBLECLK"),           
                              TEXT ("Double click y tolerance"),
     SM_CXICONSPACING,        TEXT ("SM_CXICONSPACING"),         
                              TEXT ("Horizontal icon spacing"),
     SM_CYICONSPACING,        TEXT ("SM_CYICONSPACING"),         
                              TEXT ("Vertical icon spacing"),
     SM_MENUDROPALIGNMENT,    TEXT ("SM_MENUDROPALIGNMENT"),     
                              TEXT ("Left or right menu drop"),
     SM_PENWINDOWS,           TEXT ("SM_PENWINDOWS"),            
                              TEXT ("Pen extensions installed"),
     SM_DBCSENABLED,          TEXT ("SM_DBCSENABLED"),           
                              TEXT ("Double-Byte Char Set enabled"),
     SM_CMOUSEBUTTONS,        TEXT ("SM_CMOUSEBUTTONS"),         
                              TEXT ("Number of mouse buttons"),
     SM_SECURE,               TEXT ("SM_SECURE"),                
                              TEXT ("Security present flag"),
     SM_CXEDGE,               TEXT ("SM_CXEDGE"),                
                              TEXT ("3-D border width"),
     SM_CYEDGE,               TEXT ("SM_CYEDGE"),                
                              TEXT ("3-D border height"),
     SM_CXMINSPACING,         TEXT ("SM_CXMINSPACING"),          
                              TEXT ("Minimized window spacing width"),
     SM_CYMINSPACING,         TEXT ("SM_CYMINSPACING"),          
                              TEXT ("Minimized window spacing height"),
     SM_CXSMICON,             TEXT ("SM_CXSMICON"),              
                              TEXT ("Small icon width"),
     SM_CYSMICON,             TEXT ("SM_CYSMICON"),              
                              TEXT ("Small icon height"),
     SM_CYSMCAPTION,          TEXT ("SM_CYSMCAPTION"),           
                              TEXT ("Small caption height"),
     SM_CXSMSIZE,             TEXT ("SM_CXSMSIZE"),              
                              TEXT ("Small caption button width"),
     SM_CYSMSIZE,             TEXT ("SM_CYSMSIZE"),              
                              TEXT ("Small caption button height"),
     SM_CXMENUSIZE,           TEXT ("SM_CXMENUSIZE"),            
                              TEXT ("Menu bar button width"),
     SM_CYMENUSIZE,           TEXT ("SM_CYMENUSIZE"),            
                              TEXT ("Menu bar button height"),
     SM_ARRANGE,              TEXT ("SM_ARRANGE"),               
                              TEXT ("How minimized windows arranged"),
     SM_CXMINIMIZED,          TEXT ("SM_CXMINIMIZED"),           
                              TEXT ("Minimized window width"),
     SM_CYMINIMIZED,          TEXT ("SM_CYMINIMIZED"),           
                              TEXT ("Minimized window height"),
     SM_CXMAXTRACK,           TEXT ("SM_CXMAXTRACK"),            
                              TEXT ("Maximum draggable width"),
     SM_CYMAXTRACK,           TEXT ("SM_CYMAXTRACK"),            
                              TEXT ("Maximum draggable height"),
     SM_CXMAXIMIZED,          TEXT ("SM_CXMAXIMIZED"),           
                              TEXT ("Width of maximized window"),
     SM_CYMAXIMIZED,          TEXT ("SM_CYMAXIMIZED"),           
                              TEXT ("Height of maximized window"),
     SM_NETWORK,              TEXT ("SM_NETWORK"),               
                              TEXT ("Network present flag"),
     SM_CLEANBOOT,            TEXT ("SM_CLEANBOOT"),             
                              TEXT ("How system was booted"),
     SM_CXDRAG,               TEXT ("SM_CXDRAG"),                
                              TEXT ("Avoid drag x tolerance"),
     SM_CYDRAG,               TEXT ("SM_CYDRAG"),                
                              TEXT ("Avoid drag y tolerance"),
     SM_SHOWSOUNDS,           TEXT ("SM_SHOWSOUNDS"),            
                              TEXT ("Present sounds visually"),
     SM_CXMENUCHECK,          TEXT ("SM_CXMENUCHECK"),           
                              TEXT ("Menu check-mark width"),
     SM_CYMENUCHECK,          TEXT ("SM_CYMENUCHECK"),           
                              TEXT ("Menu check-mark height"),
     SM_SLOWMACHINE,          TEXT ("SM_SLOWMACHINE"),           
                              TEXT ("Slow processor flag"),
     SM_MIDEASTENABLED,       TEXT ("SM_MIDEASTENABLED"),        
                              TEXT ("Hebrew and Arabic enabled flag"),
     SM_MOUSEWHEELPRESENT,    TEXT ("SM_MOUSEWHEELPRESENT"),     
                              TEXT ("Mouse wheel present flag"),
     SM_XVIRTUALSCREEN,       TEXT ("SM_XVIRTUALSCREEN"),        
                              TEXT ("Virtual screen x origin"),
     SM_YVIRTUALSCREEN,       TEXT ("SM_YVIRTUALSCREEN"),        
                              TEXT ("Virtual screen y origin"),
     SM_CXVIRTUALSCREEN,      TEXT ("SM_CXVIRTUALSCREEN"),       
                              TEXT ("Virtual screen width"),
     SM_CYVIRTUALSCREEN,      TEXT ("SM_CYVIRTUALSCREEN"),       
                              TEXT ("Virtual screen height"),
     SM_CMONITORS,            TEXT ("SM_CMONITORS"),             
                              TEXT ("Number of monitors"),
     SM_SAMEDISPLAYFORMAT,    TEXT ("SM_SAMEDISPLAYFORMAT"),     
                              TEXT ("Same color format flag")
} ;

So please how does this thing work...........and how are

int iIndex ;
TCHAR * szLabel ;
TCHAR * szDesc ;

related to Systemetrics.......
As some of you know I started C++ not a long time ago.......SO PLEASE NO FLAMING THE NEWBIES!!!!!!!!!

PS I know very little about C..........