/*Contact Management Database using a dynamic - single linked list
Author : P J Wells
Compiled on Dev-C++, Bloodshed Software.
Date : 03/04/08
*/
/*----------------------------------------------------------------------------*/
/* Define libraries to be included */
#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <ctype.h>
/*----------------------------------------------------------------------------*/
/* Define Functions*/
void clearInput(void);
void addNewcontact(void);
void listAll(void);
void deletecontact(void);
void modifycontact(void);
int findcontact(void);
int prompt(void);
int findnum (int);
/*----------------------------------------------------------------------------*/
/* Define Structures*/
typedef struct contact {
int number; /*unique account number*/
char name[20]; /*contains name*/
char phone[15]; /*contains phone number*/
char email[20]; /*contains email address*/
struct contact *next; /*next is used to navigate through structures.*/
int count; /*count is used to input comments into array*/
} Contact;
Contact *firstc,*currentc,*newc; /*pointers*/
/* firstc is used to point to first record in list
currentc points to current record in list
newc contains address of new structure/node
*/
int cnum = 0; /*gives unique account numbers*/
/*----------------------------------------------------------------------------*/
/* Main Function */
int main()
{
FILE *datafile;
char *filename = "contactdatabase.dat";/*declare file name*/
char ch;
firstc = NULL;
datafile = fopen(filename,"r");/* open file for reading*/
if(datafile)
{
firstc = (struct contact *)malloc(sizeof(struct contact));
/*use of malloc to set aside memory relative to size of structure contact*/
currentc = firstc; /*make first record current*/
while(1) /*endless while loop. a NULL pointer in final node ends loop*/
{
newc = (struct contact *)malloc(sizeof(struct contact));
fread(currentc,sizeof(struct contact),1,datafile);
if(currentc->next == NULL) /* NULL indicates end of node list*/
break;
currentc->next = newc; /* pointer referencing next node*/
currentc->count=0; /* initiates count for comments*/
currentc = newc; /* make current record new*/
}
fclose(datafile); /* close file - good practice to cloe files after use*/
cnum = currentc->number;
}
do
{
fflush(stdin);
puts("\nWelcome To The Contact Database");/* print menu messages*/
puts("-- -----------------------------");
puts("1 - Add a new contact");
puts("2 - Delete contact");
puts("3 - List all contacts");
puts("4 - Modify contact");
puts("5 - Find a contact by name");
puts("-- -----------------------------");
puts("Q - Save and quit\n");
printf("\tYour choice:");
ch = getchar();
ch = toupper(ch);/*changes user input case to upper case*/
switch(ch) /*stores in ch variable.*/
{
case '1':
puts("Add a new contact\n");
fflush(stdin);
addNewcontact();//call addNewcontact function
break;
case '2':
puts("Delete a contact\n");
deletecontact();
break;
case '3':
puts("List all contacts\n");
listAll();
break;
case '4':
puts("Modify a contact\n");
modifycontact();
break;
case '5':
puts("Find a contact by name\n");
findcontact();
break;
case 'Q':
puts("Save and quit\n");
default:
break;
}
}
while(ch != 'Q');
/*
* Save the records to disk
*/
currentc = firstc;
if(currentc == NULL)
return(0); /*no data to write*/
datafile = fopen(filename,"w"); /*open file to write*/
if(datafile == NULL)
{
printf("Error writing to %s\n",filename);
return(1);
}
/* Write each record to disk*/
while(currentc != NULL)
{
fwrite(currentc,sizeof(struct contact),1,datafile);
currentc = currentc->next;
}
fclose(datafile); /*closes data file*/
return(0);
}
/*----------------------------------------------------------------------------*/
void addNewcontact(void) /* add new contact function*/
{
newc = (struct contact *)malloc(sizeof(struct contact));
/*allocates memory for new structure.*/
/*
* Checks to see whether this is the first record in file
* If so, then all pointers are initialized to this record,
*/
if(firstc==NULL)
firstc = currentc = newc;
/*
* if not, end of structure list is obtained
*/
else
{
currentc = firstc; /* make the first record the current one*/
while(currentc->next != NULL)currentc = currentc->next;
/* and loop through all records*/
currentc->next = newc; /* pointer to next node */
currentc = newc; /* make current record the new one*/
}
/* update the structure */
cnum++;
printf("%27s: %5i\n","contact number",cnum);
currentc->number = cnum; /*cnum is used to give unique account numbers*/
printf("%27s: ","Enter contact name");
gets(currentc->name);
printf("%27s: ","Enter contact Phone number");
gets(currentc->phone);
printf("%27s: ","Enter contact email");
gets(currentc->email);
printf("contact added!");
currentc->count=0;
/*
* gives the new record a NULL pointer
* to show it's the last record:
*/
currentc->next = NULL;
}
/*----------------------------------------------------------------------------*/
void listAll(void) /* list all contacts function*/
{
if(firstc==NULL)
puts("There are no contacts to display!"); /*prints message*/
else
{
printf("%6s %-20s %-15s %-15s\n","Acct#","Name","Phone","Email");
puts("------ -------------------- ------------- -------------------");
/*prints table titles*/
currentc=firstc;
do
{
printf("%6d: %-20s %-15s %-20s\n",\
currentc->number,\
currentc->name,\
currentc->phone,\
currentc->email);
/*prints values of number, name, phone and email*/
}
while((currentc=currentc->next) != NULL);
}
}
/*----------------------------------------------------------------------------*/
void deletecontact(void) /*delete contact function */
{
int record;
struct contact *previousa;
if(firstc==NULL)
{
puts("There are no contacts to delete!");
return;
}
listAll(); /* show all records*/
printf("Enter contact account number to delete: ");
scanf("%d",&record);
currentc = firstc;
while(currentc != NULL)
{
if(currentc->number == record)
{
if(currentc == firstc) /*if record to be deleted is the first record*/
firstc=currentc->next; /*reset firstc to point at next record as first*/
else
previousa->next = currentc->next;/*previous pointer used if record*/
/*to delete is not the first*/
free(currentc); /*frees memory <deletes>*/
printf("contact %d deleted!\n",record);
return;
}
else
{
previousa = currentc;
currentc = currentc->next;
}
}
printf("contact %d not found!\n",record);
}
/*----------------------------------------------------------------------------*/
void modifycontact(void) /*modify contact function*/
{
int record, result;
if(firstc==NULL)
{
puts("There are no contacts to modify!");
return;
}
listAll(); /* show all records */
printf("Enter contact account number to modify or change: ");
scanf("%d",&record); /*scan user input to record*/
result = findnum(record);
if( result >0 ){
printf("Contact %d:\n",currentc->number);
printf("Name: %s\n",currentc->name);
if(prompt())
gets(currentc->name);
printf("Phone: %s\n",currentc->phone);
if(prompt())
gets(currentc->phone);
printf("Email: %s\n",currentc->email);
if(prompt())
gets(currentc->email);
return;
}
printf("contact %d was not found!\n",record);
}
/*----------------------------------------------------------------------------*/
int findnum (int recordnum)
{
int record;
record = recordnum;
currentc = firstc;
while(currentc != NULL)
{
if(currentc->number == record)
{
return 1;
}
else
{
currentc = currentc->next;
}
}
return -1;
}
/*----------------------------------------------------------------------------*/
int findcontact(void) /* find contact function*/
{
char buff[20];
if(firstc==NULL)
{
puts("There are no contacts to find!");
return 1;
}
printf("Enter contact name: ");
fflush(stdin);/*clears any text from the input stream*/
gets(buff);
currentc = firstc;
while(currentc != NULL)
{
if( strcmp(currentc->name, buff) == 0 )
{
printf("%6s %-20s %-15s %-15s\n","Acct#","Name","Phone","Email");
/*prints table titles*/
printf("%6d: %-20s %-15s %-20s\n",\
currentc->number,\
currentc->name,\
currentc->phone,\
currentc->email);
/*prints values of number, name, phone and email*/
return 0;
}
else
{
currentc = currentc->next;
}
}
printf("contact %s was not found!\n",buff);
return 1;
}
/*----------------------------------------------------------------------------*/
int prompt(void)
{
char ch;
fflush(stdin);
printf("Update? (Y to update any other key to not)");
ch = getchar();
ch = toupper(ch);
fflush(stdin);
if(ch == 'Y')
{
printf("Enter new value: ");
return(1);
}
else
return(0);
}
/*----------------------------------------------------------------------------*/
/* END OF PROGRAM */
