i need to write a program that is acting as a simple personal address book with the record of name,email and phone numbers.
The range of function should have:
searching existing records.
adding new records.
deleting existing records.
i need to include the last update date and time of the record in the form of dd-mm-yyyy,hh:mm:ss(it has to be updated by th program automatically) and i don't really know how. Can't someone help me? I'm new to C language. And there is some problem in the delete function, edit function and the file operation.
Below is the code of what my group members and I did so far

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

enum {
    MAXLEN=255
};

typedef struct list {
    char name[MAXLEN];
    char address[MAXLEN];
    char phone[MAXLEN];
    struct list *next;
} ADDRESS;

void add_to_list (void);
void delete_from_list (void);
void search_name (void);
void list_names (void);
void quit_program (void);
void edit(void);
ADDRESS *hol= NULL;

int main()
{
    char input[MAXLEN];


    while (1) {
        printf ("What you want to do?\n");
        printf("a.Search\n");
        printf("b.Add\n");
        printf("c.Delete\n");
        printf("d.Edit\n");
        printf("e.Display Option\n");
        printf("f.Exit\n");


        fgets (input, MAXLEN,stdin);
        switch (input[0]) {
            case ('a'):
            case ('A'):
                search_name();
                break;
            case ('b'):
            case ('B'):
                add_to_list();
                break;
            case ('c'):
            case ('C'):
                delete_from_list();
                break;
            case ('d'):
            case ('D'):
                edit();
                break;
            case ('e'):
            case ('E'):
                quit_program();
                return (0);
            default:
                printf ("Unknown command\n");
        }

    }
    return 0;
}

void add_to_list (void)

{
    ADDRESS *new_name;

    new_name= (ADDRESS *)malloc (sizeof (ADDRESS));
    if (new_name == NULL) {
        printf ("Out of memory!\n");
        exit (-1);
    }

    printf ("Name> ");
    fgets (new_name->name, MAXLEN, stdin);
    printf ("Address> ");
    fgets (new_name->address, MAXLEN, stdin);
    printf ("Tel> ");
    fgets (new_name->phone, MAXLEN, stdin);
    /* Chain the new item into the list */
    new_name->next= hol;
    hol= new_name;
}

void delete_from_list (void)

{
    ADDRESS *del_ptr;   /* Pointer to find name to delete */
    ADDRESS *prev_ptr;  /* Pointer to name BEFORE this name */
    char del_name[MAXLEN]; /* Name to delete */

    printf ("Name> ");
    fgets (del_name, MAXLEN, stdin);

    if (hol == NULL) {
        printf ("No list to delete from\n");
        return;
    }
    if (strcmp(hol->name, del_name) == 0) {
        del_ptr= hol;
        hol= hol->next;
        free(del_ptr);
        return;
    }

    prev_ptr= hol;
    while (prev_ptr->next != NULL) {

        if (strcmp(prev_ptr->next->name,del_name) == 0) {
            del_ptr= prev_ptr->next;
            prev_ptr->next= del_ptr->next;
            free(del_ptr);
            return;
        }
        prev_ptr= prev_ptr->next;
    }
    printf ("Name not found!\n");
}

void search_name (void)


{
    char name[MAXLEN];  /* Name to look for */
    ADDRESS *search_ptr;
    printf ("Name> ");
    fgets (name, MAXLEN, stdin);
    search_ptr= hol;
    while (search_ptr != NULL) {
        if (strcmp (search_ptr->name, name) == 0) {
            printf ("Address: %s", search_ptr->address);
            printf ("Tel: %s", search_ptr->phone);
            return;
        }
        search_ptr= search_ptr->next;
    }
    printf ("No such name\n");
}

void list_names (void)

{
    ADDRESS *tmp_ptr; /* Traverses list */
    printf ("All names in address book:\n");
    tmp_ptr= hol;
    while (tmp_ptr != NULL) {
        printf ("%s",tmp_ptr->name);
        tmp_ptr= tmp_ptr->next;
    }
}

void quit_program (void)
{
    ADDRESS *del_ptr;

    while (hol != NULL) {
       del_ptr= hol;
       hol= hol->next;
       free(del_ptr);
    }
}


void edit (void)

{
    ADDRESS *edi_ptr;   /* Pointer to find name to edit */
    ADDRESS *prev_ptr;  /* Pointer to name BEFORE this name */
    char edi_name[MAXLEN]; /* Name to edit */

    printf ("Name> ");
    fgets (edi_name, MAXLEN, stdin);

    if (hol == NULL) {
        printf ("No list to edit from\n");
        return;
    }
    if (strcmp(hol->name, edi_name) == 0) {
        edi_ptr= hol;
        hol= hol->next;
        free(edi_ptr);
        return;
    }

    prev_ptr= hol;
    while (prev_ptr->next != NULL) {

        if (strcmp(prev_ptr->next->name,edi_name) == 0) {
            edi_ptr= prev_ptr->next;
            prev_ptr->next= edi_ptr->next;
            free(edi_ptr);
            return;
        }
        prev_ptr= prev_ptr->next;
    }
    printf ("Name not found!\n");
}

>>i need to include the last update date and time of the record in the form of dd-mm-yyyy,hh:mm:ss(it has to be updated by th program automatically) and i don't really know how.

Just add another field called UpdateDateTime (or whatever you want to call it) to each record which would be time_t. When you write a record get the system's time using time() function from time.h and save it to the field along with all the other information. If you don't want to save the date/time as an integer then you can call localtime() that returns a string and save that, but it will take up alot more space in the file.

oh..ok..thank you so much!!now i have no problem with the time and date thingy..but still have another question that is on exiting the program all active records must be stored in a file eg. phonebook.txt. On start up, the program should read the stored file and display records on the screen.If the file does't exist, have to create a new one to store information. The program should prompt the user for input to perform the functions listed above.
Which function i need to use? and how?

you need to use FILE*. On program startup, attempt to open the file for reading. If successful, then do what you mentioned. If not, then the file doesn't exist.

>>Which function i need to use? and how?
This is just normal file i/o stuff that should be explained in your textbook.

fopen() -- opens the file
fread() and fgets() -- reads the file
fwrite() -- writes the file
fseek() -- move file pointer around the file
fclose() -- close the file

now my program can be saved, however when i want to delete a contact, it can't be deleted completely, what's wrong?

void delete_from_list (void)

{
    ADDRESS *del_ptr;   /* Pointer to find name to delete */
    ADDRESS *prev_ptr;  /* Pointer to name BEFORE this name */
    char del_name[MAXLEN]; /* Name to delete */

    printf ("Name> ");
    fgets (del_name, MAXLEN, stdin);

    if (hol == NULL) {
        printf ("No list to delete from\n");
        return;
    }
    if (strcmp(hol->name, del_name) == 0) {
        del_ptr= hol;
        hol= hol->next;
        free(del_ptr);
        return;
    }

    prev_ptr= hol;
    while (prev_ptr->next != NULL) {

        if (strcmp(prev_ptr->next->name,del_name) == 0) {
            del_ptr= prev_ptr->next;
            prev_ptr->next= del_ptr->next;
            free(del_ptr);
            return;
        }
        prev_ptr= prev_ptr->next;
    }
    printf ("Name not found!\n");
}
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