Question

I need to add the following to this program

1) Alphabetically sort the list of entries by name (first or last).

2) Find a phone number for a given name.

3) Randomly select a friend from the phonebook for you to call.

4) Delete everyone from the phonebook at the same time.

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

typedef struct contact {
char firstname[20];
char lastname[20];
char phoneNumber[15];
struct contact * next;
struct contact * prev;
}contact;

typedef enum {
FALSE,
TRUE
}boolean;

contact * head = NULL;

contact * insert(contact * head, contact * new_data) {
if (head == NULL) {
head = new_data;
} else {
new_data -> next = head;
new_data -> prev = NULL;
head -> prev = new_data;
head = new_data;
}

return head;
}
contact * search(contact * head, char first_name[], char last_name[]) {
contact * temp = head;
while (temp != NULL) {
if ((strcmp(temp -> firstname, first_name) == 0) && (strcmp(temp -> lastname, last_name) == 0)) {
return temp;
}
temp = temp -> next;
}
return NULL;
}
boolean isValid(char phoneNumber[]) {
   int i;
for (i = 0; phoneNumber[i] != '\0'; i++) {
if ((!isdigit(phoneNumber[i])) && (phoneNumber[i] != '-')) {
return FALSE;
}
}

return TRUE;
}

int main() {
int choice = 0;
while (choice != 4) {
printf("1.To insert\n2.To delete\n3.To display phonebook\n4.To exit\n");
scanf("%d", & choice);
switch (choice) {
case 1: {
contact * new_data = (contact * ) malloc(sizeof(contact));
char first_name[20], last_name[20], phoneNumber[15];
printf("First Name: ");
scanf("%s", first_name);
printf("Last Name: ");
scanf("%s", last_name);
printf("Phone Name: ");
scanf("%s", phoneNumber);

strcpy(new_data -> firstname, first_name);
strcpy(new_data -> lastname, last_name);
strcpy(new_data -> phoneNumber, phoneNumber);
head = insert(head, new_data);
break;
}
case 2: {
contact * old_data, * prev_temp, * next_temp;
char first_name[20], last_name[20];
printf("First Name: ");
scanf("%s", first_name);
printf("Last Name: ");
scanf("%s", last_name);
old_data = search(head, first_name, last_name);
if (old_data -> prev != NULL) {
prev_temp = old_data -> prev;
prev_temp -> next = old_data -> next;
} else {
head = old_data -> next;
}
if (old_data -> next != NULL) {
next_temp = old_data -> next;
next_temp -> prev = old_data -> prev;
}

break;
}
case 3: {
contact * temp = head;
while (temp != NULL) {
if (isValid(temp -> phoneNumber) == TRUE) {
printf("FIRST NAME: %s\t", temp -> firstname);
printf("LAST NAME: %s\t", temp -> lastname);
printf("PHONE NUM: %s\n", temp -> phoneNumber);
}
temp = temp -> next;
}
break;
}
case 4: {
break;
}
default:
printf("Not a valid choice[1-4]\n");
}
}

}

Answer 1

I've created the program from scratch and not using the template cause I didn't understand that easily and I felt easy to write a program from scratch. (Due to the indentation and not availability of comments I didn't understand the program)

Program: (C)

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

//Function prototypes
void Add();
void Delete();
void Display();
void Alphabetical();
void Number();
void Random();
void DeleteAll();

//Structure for Phonebook list
typedef struct PhoneBookList {
    char *FirstName;
    char *LastName;
    char *PhoneNumber;  
}list;

//Structure for delete
typedef struct DeleteEntry {
    char *FirstName;
    char *LastName;
}take;


//Pointers to structures
list *lt;
take *tk;

//Global variables
int count = 0;
int delCount = 0;

int main(void) 
{ 
        //Variable declarations
        int iSelection;
        do 
        {
          //Print menu to screen, ask user for selection
          printf("Phone Book:\n\n");
          printf(" 1) Add friend\n");
          printf(" 2) Delete friend\n");
          printf(" 3) Display phone book\n");
          printf(" 4) Sort and display entries alphabetically by last name\n");
          printf(" 5) Find phone number for given name\n");
          printf(" 6) Randomly select contact\n");
          printf(" 7) Delete all contacts\n");
          printf(" 8) Exit\n");
          printf(" What do you want to do? \n");
          scanf("%d", &iSelection);
        
          switch (iSelection) 
          {
               case 1:  //Add entry
                    Add();  
                    break;
               
               case 2:  //Delete entry
                    Delete();
                    break;
                    
               case 3:  //Display all entries
                    Display();
                    break;
                    
               case 4: //Sort entries alphabetically
                    Alphabetical();
                    break;
                    
               case 5: //Find phone number
                    Number();
                    break;
                    
               case 6: //Randomly select contact
                    Random();
                    break;
                    
               case 7: //Delete all contacts
                    DeleteAll();
                    break;
                    
               case 8: //Break loop and close program
                    break;
               
               default:  //User entered an invalid number
                    printf("\nYou entered an invalid selection.  Try again.\n");
                    break;
               
            } //End Switch           
          } while (iSelection != 8);  //End Do While loop
          
          //Return used memory
          free(tk);
          free(lt);
          tk = NULL;
          lt = NULL;
          return 0; 
} //End Main


//Add an entry
void Add()
{ 
    char *leftName;
     
    if (count == 0) 
    {
        lt = (list *) malloc ((count*25) + 25);
    }
    else
    {
        lt = (list *) realloc (lt, (count*50) + 50);
    }
    
    if (lt == NULL)
    {
       printf("You cannot add more memory\n");
    }
    else
    {
       lt[count].FirstName = (char *) malloc(sizeof(char)*15);
       lt[count].LastName = (char *) malloc(sizeof(char)*15);
       lt[count].PhoneNumber = (char *) malloc(sizeof(char)*15);
       printf("\nEnter their First Name: ");
       scanf("%s", lt[count].FirstName);
       printf("\nEnter their Last Name: ");
       scanf("%s", lt[count].LastName);
       printf("\nEnter their Phone Number: ");
       scanf("%s", lt[count].PhoneNumber);
       printf("\nContact added\n");      
    }
    count++;
}//End Function

//Delete an entry
void Delete()
{
    int i;
    int q = 0;
    char *userName;
    if (delCount == 0) 
    {
        tk = (take *) malloc ((delCount*25) + 25);
    }
    else
    {
        tk = (take *) realloc (tk, (delCount*1) + 1);
    }
     
        if (tk == NULL)
        {
            printf("This cannot be deleted (out of memory)\n");
        }
        else
        {
            tk[delCount].FirstName = (char *) malloc(sizeof(char)*15);
            tk[delCount].LastName = (char *) malloc(sizeof(char)*15);
            printf("\nEnter their First Name: ");
            scanf("%s", tk[delCount].FirstName);
            printf("\nEnter their Last Name: ");
            scanf("%s", tk[delCount].LastName);
        }
        
        for (i = 0; i < count; i++)
        {
                if (lt[i].FirstName == NULL && lt[i].LastName == NULL) 
                        continue;
                        if (strcmp(lt[i].FirstName, tk[delCount].FirstName) == 0 && strcmp(lt[i].LastName, tk[delCount].LastName) == 0)
                        {
                            printf("\n%s %s has been deleted\n", lt[i].FirstName, lt[i].LastName);
                            lt[i].FirstName = NULL;
                            lt[i].LastName = NULL;
                            lt[i].PhoneNumber = NULL;
                            q = 1;
                            break;
                        }
    } //End for loop                       
         
        if (q != 1)
        {
                printf("\nThis person is not in the Phonebook\n");
        }
                delCount++;
                count--;
}//End function

//Display all phonebook entries
void Display()
{
    int i;
    printf("\nYour contacts:\n"); 
    for (i = 0; i < count; i++)
    {
        if (lt[i].FirstName != NULL && lt[i].LastName != NULL)
        {
            printf("\n%s %s: %s\n", lt[i].FirstName, lt[i].LastName, lt[i].PhoneNumber);
        }
    }//End for loop
    system("pause");
}//End function

//Sort entries alphabetically by last name.
void Alphabetical()
{
    int i;
    int j;
    char temp[50][50]; 
    printf("\nYour contacts:\n");
    
    for (i = 0; i < count; i++)
    {
        for (j = i + 1; j < count; j++)
        {
            if (strcmp(lt[i].LastName, lt[j].LastName) > 0)
            {
                strcpy(temp[i], lt[i].LastName);
                strcpy(lt[i].LastName, lt[j].LastName);
                strcpy(lt[j].LastName, temp[i]);
            }
        }
    }//End for loop

    for (i = 0; i < count; i++)
        printf("\n%s %s: %s\n", lt[i].FirstName, lt[i].LastName, lt[i].PhoneNumber); 
        system("pause");
}//End function  

//Find phone number for given name
void Number()
{  
    int i;
        int q = 0;
    char fName[25];
    char lName[25];
     
    printf("\nEnter their First Name: ");
    scanf("%s", fName);
    printf("\nEnter their Last Name: ");
    scanf("%s", lName);
       
    for (i = 0; i < count; i++)
    {
        if (strcmp(lt[i].FirstName, fName) == 0 && strcmp(lt[i].LastName, lName) == 0)
        {
            printf("\n%s %s's phone number is:  %s\n", lt[i].FirstName, lt[i].LastName, lt[i].PhoneNumber);
            q = 1;
            break;
        }
    }
     
    if (q != 1)
    {
                printf("\nThis person is not in the Phonebook\n");
    }
    system("pause");
}//End function

//Randomly select contact
void Random()
{
        srand(time(NULL));  
        int iRandomNum;   
        iRandomNum = (rand() % count) + 1;
        printf("%s %s:  %s\n", lt[iRandomNum].FirstName, lt[iRandomNum].LastName, lt[iRandomNum].PhoneNumber);
        system("pause");
}//End function

//Delete everyone from phone book
void DeleteAll()
{
    int i;
     
    for (i = 0; i < count; i++)
    {
        do
                {
            lt[i].FirstName = NULL;
            lt[i].LastName = NULL;
            lt[i].PhoneNumber = NULL;
            break;    
        } while (i <= count); 
        }
     
    printf("\nAll contacts deleted\n\n");
    system("pause");
     
}//End function

----------------------------------------------------------------------------------------------------------------------------------------------------------Feel free to ask you doubts in the comments.