Tâche à l'aide .txt fichier et le répertoire de programme en C

Ci-dessous mon code pour un répertoire de programme en C. je vais avoir de la difficulté à le modifier. J'ai besoin de le modifier, de sorte que, après l'ajout d'entrées à l'annuaire , le contenu sera écrite dans un .fichier txt. Après la suppression d'une entrée j'ai besoin du contenu d'être écrite à la même .fichier txt et ont tout le contenu de l'imprimé. Suis-je censé utiliser fopen () la fonction? Je suis un débutant...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct Phonebook_Contacts
{
char FirstName[20]; 
char LastName[20];
char PhoneNumber[20]; 
} phone; 
void AddEntry(phone * ); 
void DeleteEntry(phone * ); 
void PrintEntry(phone * );
void SearchForNumber(phone * ); 
void RandomName(phone * ); 
void DeleteAll(phone * ); 
void FreeContacts (phone * ); 
int counter = 0; 
char FileName[256]; 
FILE *pRead; 
FILE *pWrite; 
int main (void)
{      
phone *phonebook; 
phonebook = (phone*) malloc(sizeof(phone)*100); 
int iSelection = 0; 
if (phonebook == NULL)
{
printf("Out of Memory. The program will now exit");
return 1;
}
else {} 
do
{
printf("\n\t\t\tPhonebook Menu");
printf("\n\n\t(1)\tAdd Friend");
printf("\n\t(2)\tDelete Friend");
printf("\n\t(3)\tDisplay Phonebook Entries");
printf("\n\t(4)\tSearch for Phone Number");
printf("\n\t(5)\tFind a Random Friend");
printf("\n\t(6)\tDelete All Entries");
printf("\n\t(7)\tExit Phonebook");
printf("\n\nWhat would you like to do? ");
scanf("%d", &iSelection);  
if (iSelection == 1)
{
AddEntry(phonebook); 
} 
if (iSelection == 2)
{
DeleteEntry(phonebook); 
} 
if (iSelection == 3)
{
PrintEntry(phonebook); 
} 
if (iSelection == 4)
{
SearchForNumber(phonebook);         
} 
if (iSelection == 5)
{
RandomName(phonebook);         
} 
if (iSelection == 6)
{
DeleteAll(phonebook); 
} 
if (iSelection == 7)
{
printf("\nYou have chosen to exit the Phonebook.\n");
system("pause");
FreeContacts(phonebook);
return 0;
} 
} while (iSelection <= 9); 
} 
void AddEntry (phone * phonebook)
{  
pWrite = fopen("phonebook_contacts.dat", "a");
if ( pWrite == NULL )
{
perror("The following error occurred ");
exit(EXIT_FAILURE); 
}
else
{
counter++; 
realloc(phonebook, sizeof(phone)); 
printf("\nFirst Name: ");
scanf("%s", phonebook[counter-1].FirstName);
printf("Last Name: ");
scanf("%s", phonebook[counter-1].LastName);
printf("Phone Number (XXX-XXX-XXXX): "); 
scanf("%s", phonebook[counter-1].PhoneNumber);
printf("\n\tFriend successfully added to Phonebook\n"); 
fprintf(pWrite, "%s\t%s\t%s\n", phonebook[counter-1].FirstName, phonebook[counter-1].LastName, phonebook[counter-1].PhoneNumber);
fclose(pWrite); 
} 
} 
void DeleteEntry (phone * phonebook)
{
int x = 0;
int i = 0;
char deleteFirstName[20];  //
char deleteLastName[20];  
printf("\nFirst name: ");
scanf("%s", deleteFirstName);
printf("Last name: ");
scanf("%s", deleteLastName);
for (x = 0; x < counter; x++)
{
if (strcmp(deleteFirstName, phonebook[x].FirstName) == 0) 
{
if (strcmp(deleteLastName, phonebook[x].LastName) == 0) 
{
for ( i = x; i < counter - 1; i++ )
{
strcpy(phonebook[i].FirstName, phonebook[i+1].FirstName); 
strcpy(phonebook[i].LastName, phonebook[i+1].LastName); 
strcpy(phonebook[i].PhoneNumber, phonebook[i+1].PhoneNumber); 
} 
printf("Record deleted from the phonebook.\n\n");
--counter; 
return;
} 
} 
}    
printf("That contact was not found, please try again.");
}
void PrintEntry (phone * phonebook)
{
int x = 0;
printf("\nPhonebook Entries:\n\n ");
pRead = fopen("phonebook_contacts.dat", "r");
if ( pRead == NULL)
{
perror("The following error occurred: ");
exit(EXIT_FAILURE);
}
else
{
for( x = 0; x < counter; x++) 
{
printf("\n(%d)\n", x+1); 
printf("Name: %s %s\n", phonebook[x].FirstName, phonebook[x].LastName); 
printf("Number: %s\n", phonebook[x].PhoneNumber); 
} 
} 
fclose(pRead);
} 
void SortByFirstName (phone * phonebook)
{
int i = 0;
int x = 0;
int swap;
int TempCounter = counter;
phone Temp; 
do
{
swap = 0;
for(i = 1; i < TempCounter; i++)
{
if(strcmp(phonebook[i-1].FirstName, phonebook[i].FirstName) > 0)
{
Temp = phonebook[i]; 
phonebook[i] = phonebook[i-1]; 
phonebook[i-1] = Temp; 
strcpy(Temp.FirstName, phonebook[i].FirstName);
strcpy(Temp.LastName, phonebook[i].LastName);
strcpy(Temp.PhoneNumber, phonebook[i].PhoneNumber);
swap = 1;
}
} 
TempCounter--;
} while (swap); 
printf("\nYour friends in Alphabetical Order by First Name:\n\n");
for( x = 0; x < counter; x++ )
{
printf("\n(%d)\n", x+1); 
printf("Name: %s %s\n", phonebook[x].FirstName, phonebook[x].LastName); 
printf("Number: %s\n", phonebook[x].PhoneNumber); 
}   
} 
void SortByLastName (phone * phonebook)
{
int i = 0;
int x = 0;
int swap;
int TempCounter = counter;
phone Temp; 
do
{
swap = 0;
for(i = 1; i < TempCounter; i++)
{
if(strcmp(phonebook[i-1].LastName, phonebook[i].LastName) > 0)
{
Temp = phonebook[i]; 
phonebook[i] = phonebook[i-1]; 
phonebook[i-1] = Temp;
strcpy(Temp.FirstName, phonebook[i].FirstName);
strcpy(Temp.LastName, phonebook[i].LastName);
strcpy(Temp.PhoneNumber, phonebook[i].PhoneNumber);
swap = 1;
} 
} 
TempCounter--;
} while (swap); 
printf("\nYour friends in Alphabetical Order by First Name:\n\n");
for( x = 0; x < counter; x++ )
{
printf("\n(%d)\n", x+1); 
printf("Name: %s %s\n", phonebook[x].FirstName, phonebook[x].LastName); 
printf("Number: %s\n", phonebook[x].PhoneNumber); 
}                 
} 
void SearchForNumber (phone * phonebook)
{
int x = 0;
char TempFirstName[20]; 
char TempLastName[20]; 
printf("\nPlease type the name of the friend you wish to find a number for.");
printf("\n\nFirst Name: ");
scanf("%s", TempFirstName);
printf("Last Name: ");
scanf("%s", TempLastName);
for (x = 0; x < counter; x++)
{
if (strcmp(TempFirstName, phonebook[x].FirstName) == 0) 
{
if (strcmp(TempLastName, phonebook[x].LastName) == 0) 
{
printf("\n%s %s's phone number is %s\n", phonebook[x].FirstName, phonebook[x].LastName, phonebook[x].PhoneNumber);
} 
} 
}     
} 
void RandomName (phone * phonebook)
{
int iRandom = 0;
srand(time(NULL));
iRandom = rand() % counter;  
int x = iRandom; 
printf("\nYour random friend is: %s %s\n", phonebook[x].FirstName, phonebook[x].LastName);
printf("Their phone number is: %s\n", phonebook[x].PhoneNumber);
}    
void DeleteAll (phone * phonebook)
{
int x = 0;
char nullStr[20] = {'\0'}; 
for ( x = 0; x < counter; x++ )
{
strcpy(phonebook[x].FirstName, nullStr); 
strcpy(phonebook[x].LastName, nullStr); 
strcpy(phonebook[x].PhoneNumber, nullStr); 
--counter; 
}   
printf("All Contacts have been deleted.\n");     
} 
void FreeContacts (phone * phonebook)
{
--counter;
for ( ; counter > 0; --counter)
{
free(phonebook[counter].FirstName); 
free(phonebook[counter].LastName); 
free(phonebook[counter].PhoneNumber); 
free(phonebook); 
counter = 0; 
return; 
}
}