Thread: Sorting Alphabetically problem

In my phone book program I need to give the user the option to sort their contacts alphabetically. I've managed to sort the Last names alphabetically, but the persons First name and Phone number are not sorting with their last name. Its like this:

eric c. 555-5555
steve a. 444-4444
mike b. 333-3333

when sorted alphabetically becomes:

eric a. 555-5555
steve b. 444-4444
mike c. 333-3333

Could I use something like strcat() to combine everything and then just sort by first name? Any other suggestions? I'm not sure how to approach this. Here's my entire program.

Code:

#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("\n\nPhone 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? ");
        
          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

//Function definitions

//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

What bernt said... ( beat me to it by mere seconds...)

Plus you could make your life a lot simpler if you did this...

Code:

//Structure for Phonebook list
typedef struct PhoneBookList {
        
        char FirstName[16];
        char LastName[16];
        char PhoneNumber[16];
} list;

That lets you get rid of all the malloc() calls you're making since the data is right in the struct. It also lets you enter data directly into the struct...

Yes, you can, but you don't probably want to.

You should be using a struct to group together the different parts of each record.

One person equals one record and equals one struct in C. I use the terms record and struct, and field and member, interchangeably so don't get confused.

Code:

struct student {
   char lname[26];   //these are fields or struct members
   char fname[26];   //use the dot operator to access
   char phone[8];     //or a pointer to the struct and ->
   char areaCode[4];
};

Add fields as needed. This goes in global space, before main().

Then declare the array of structs in main, and pass around as needed to your other functions.

Code:

struct student studs[1000]; //array of structs, 

//Then in your sorting code, you can compare fields:

if(studs[i].phone > studs[i+1].phone) {
   //you can also swap structs directly
   tempStud = studs[i];
   studs[i] = studs[i+1];
   studs[i+1] = tempStud;
}

Edit: Nina posted again!

Originally Posted by Adak

Then declare the array of structs in main, and pass around as needed to your other functions.

Code:

struct student studs[1000]; //array of structs, 

//Then in your sorting code, you can compare fields:

if(studs[i].phone > studs[i+1].phone) {
   //you can also swap structs directly
   tempStud = studs[i];
   studs[i] = studs[i+1];
   studs[i+1] = tempStud;
}

Edit: Nina posted again!

Actually I'm pretty shure you don't want to declare an array of 1000 structs... on the stack inside main.

This is one case where one should "go global" or you can declare it in main with static scope.

Yeeeeepppp! ^^^^

malloc can give you 1000 structs.... probably.

Originally Posted by whiteflags

malloc can give you 1000 structs.... probably.

that too!