------------ program 5.2 ---------------------
/* Program 5.2 from PTRTUT10.HTM               6/13/97 */
#include <stdio.h>
#include <string.h>
struct tag{                                /*  the structure type */
     char lname[20];                       /*  last name */
     char fname[20];                       /*  first name */
     int age;                              /*  age */
     float rate;                           /*  e.g. 12.75 per hour */
};
struct tag my_struct;                      /* define the structure */
void show_name(struct tag *p);             /* function prototype */
int main(void)
{
     struct tag *st_ptr;                   /* a pointer to a structure */
     st_ptr = &my_struct;                  /* point the pointer to my_struct */
     strcpy(my_struct.lname,"Jensen");
     strcpy(my_struct.fname,"Ted");
     printf("\n%s ",my_struct.fname);
     printf("%s\n",my_struct.lname);
     my_struct.age = 63;
     show_name(st_ptr);                    /* pass the pointer */
     return 0;
}
void show_name(struct tag *p)
{
     printf("\n%s ", p->fname);            /* p points to a structure */
     printf("%s ", p->lname);
     printf("%d\n", p->age);
}
-------------------- end of program 5.2 ----------------

Again, this is a lot of information to absorb at one time. The reader should compile and run the various code snippets and using a debugger monitor things like my_struct and p while single stepping through the main and following the code down into the function to see what is happening.