程序代码：

#include <stdlib.h>
#include <stdio.h>

#ifndef NULL
#define NULL 0
#endif

struct list
{
    char *ch;
    struct list *next_rec;
};

typedef struct list LIST;
typedef LIST *LISTPTR;

LISTPTR add_to_list(char *, LISTPTR);
void show_list(LISTPTR);
void free_memory_list(LISTPTR);

LISTPTR first = NULL;

int main(void)
{

    int i = 0;
    char *ch;
    
    ch = (char *)malloc(40);

    while(i++ < 5)
    {
        printf("\nEnter name %d,", i);

        do
        {
            printf("\nPlease enter a name(<=40):  ");
            gets(ch);
        }while( (*ch < 'a' || *ch > 'z') && ( *ch < 'A' || *ch > 'Z') );

        add_to_list(ch, first);
    }
    show_list(first);
    free_memory_list(first);
    return 0;
}

LISTPTR add_to_list( char *ch, LISTPTR first)
{
    LISTPTR new_rec = NULL;
    LISTPTR tmp_rec = NULL;
    LISTPTR prev_rec = NULL;

    if((new_rec = (LISTPTR)malloc(sizeof(LIST)) ) == NULL)
    {
        fprintf(stderr, "\nUnable to allocate memory!\n");
        exit(1);
    }

    new_rec->ch = ch;
    new_rec->next_rec = NULL;

    if(first == NULL)
    {
        first = new_rec;
        new_rec->next_rec = NULL;
    }
    else
    {
        if(strcmp(new_rec -> ch, first -> ch) < 0)
        {
            new_rec -> next_rec = first;
            first = new_rec;
        }
        else
        {
            while ( tmp_rec -> next_rec != NULL)
            {
                if( strcmp(new_rec->ch, tmp_rec->ch) < 0)
                {
                    new_rec->next_rec = tmp_rec;
                    if(new_rec->next_rec != prev_rec->next_rec)
                    {
                        fprintf(stderr, "ERROR");
                        getc(stdin);
                        exit(1);
                    }
                    prev_rec->next_rec = new_rec;
                    break;
                }
                else
                {
                    tmp_rec = first -> next_rec;
                    prev_rec = prev_rec->next_rec;
                }
            }

            if(tmp_rec->next_rec == NULL)
            {
                if(strcmp(new_rec->ch, tmp_rec->ch) < 0)
                {
                    new_rec->next_rec = tmp_rec;
                    prev_rec->next_rec = new_rec;
                }
                else
                {
                    tmp_rec = tmp_rec -> next_rec;
                    prev_rec = prev_rec -> next_rec;
                }
            }
        }
    }
    return(first);
}

void show_list(LISTPTR first)
{
    LISTPTR cur_ptr;
    int counter = 1;

    printf("\n\nRec addr    Position    Data    Next Rec addr\n");
    printf("========================================\n");

    cur_ptr = first;
    while(cur_ptr != NULL)
    {
        printf("    %p    ", cur_ptr);
        printf("    %2i    %s", counter++, cur_ptr->ch);
        printf("    %p    \n", cur_ptr->next_rec);
        cur_ptr = cur_ptr->next_rec;
    }
}

void free_memory_list(LISTPTR first)
{
    LISTPTR cur_ptr, next_rec;
    cur_ptr = first;

    while(cur_ptr != NULL)
    {
        next_rec = cur_ptr->next_rec;
        free(cur_ptr);
        cur_ptr = next_rec;
    }
}