C语言使用指向结构的指针

/* names1.c -- uses pointers to a structure */
#include <stdio.h>
#include <string.h>

#define NLEN 30
struct namect {
    char fname[NLEN];
    char lname[NLEN];
    int letters;
};

void getinfo(struct namect *);
void makeinfo(struct namect *);
void showinfo(const struct namect *);
char * s_gets(char * st, int n);

int main(void)
{
    struct namect person;

    getinfo(&person);
    makeinfo(&person);
    showinfo(&person);
    return 0;
}

void getinfo (struct namect * pst)
{
    printf("Please enter your first name.\n");
    s_gets(pst->fname, NLEN);
    printf("Please enter your last name.\n");
    s_gets(pst->lname, NLEN);
}

void makeinfo (struct namect * pst)
{
    pst->letters = strlen(pst->fname) +
    strlen(pst->lname);
}

void showinfo (const struct namect * pst)
{
    printf("%s %s, your name contains %d letters.\n",
           pst->fname, pst->lname, pst->letters);
}

char * s_gets(char * st, int n)
{
    char * ret_val;
    char * find;

    ret_val = fgets(st, n, stdin);
    if (ret_val)
    {
        find = strchr(st, '\n');   // look for newline
        if (find)                  // if the address is not NULL,
            *find = '\0';          // place a null character there
        else
            while (getchar() != '\n')
                continue;          // dispose of rest of line
    }
    return ret_val;
}