20 error in this code!

[parksie]

struct {
	int iIndex;
	char * szlabel;
	char * szdesc;
}

This defines a structure. The next bit is just a statically-allocated array of these structures, initialised as you can see.

#define NUMLINES (int)(sizeof sysmetrics / sizeof sysmetrics [0])

This cryptic-looking line is actually quite simple. It divides the size in bytes of the ENTIRE array by the size of one of those elements, giving the number of items entered. It's a quicker way that counting them and hard-coding that number.