Task using .txt file and phonebook program in C - c

Question

Below is my code for a phonebook program in C. I'm having trouble modifying it. I need to modify it so that after adding entries to the phonebook , the contents will be written to a .txt file. After deleting an entry I need the contents to be written to the same .txt file and have the entire contents printed. Am I supposed to use the fopen () function? I'm a beginner...
#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;
}
}

Answer 1

Are you sure you want to be doing "realloc(phonebook, sizeof(phone));" in your AddEntry() function? That's almost certainly not doing what you think it is.

Answer 2

Pretty much all the code you need is already here in this program. I would recommend you start by looking up tutorials or reading the file I/O chapter of books. An additional resource for you is the man pages for the C functions. If you're on a *NIX system you can type man fopen or you can type that into Google to get the same results on a windows system.
Here's the man page for fopen(). As you can see there are two parameters, the name of the file you want to open and the mode.
Clearly there are options to open a file for writing there as well as appending a file that already exists.
You mentioned a requirement to write to a .txt file, in your code you're opening a .dat file phonebook_contacts.dat is this the file you were talking about?
One of the easiest options is to read the entire file into memory then change it there and write it back to the file (over write the existing file), but it's not efficent as you'll have to loop over each existing element and copy them into you phonebook variable. You might want to check with your instructor to see if this is an acceptable solution. Something like:
while( more to read){
read fname line
strcpy(phonebook[i].first_name, fname)
read lname line
strcpy(phonebook[i].last_name, fname)
read num line
strcpy(phonebook[i].number, num)
increment i
}