http://kor.i2p/books/The%20C%20Programming%20Language%20by%20K&R/chapter6.html
A member of a particular structure is referred to in an expression by a
construction of the form structure-name.member The structure member operator ``.'' connects the structure name and the
member name. To print the coordinates of the point pt , for instance, printf("%d,%d", pt.x, pt.y); or to compute the distance from the origin (0,0) to pt , double dist, sqrt(double);
dist = sqrt((double)pt.x * pt.x + (double)pt.y * pt.y); Structures can be nested.