Search and Delete In Linked List

[Schwagmister]

Hello,
I need some help with my search and delete functions if anyone could help me figure out why they are not working correctly that would be wonderful!

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

struct Node
{
    char firstName [15];
    char lastName [15];
    char Number [15];
    char searchName [15];
    struct Node *next;
} ;

struct Node *Head = NULL;

int printInfoRecieveOption () ;
void clearScreen () ;
void insertEntry ();
void printAll ();
void findEntry (char name []) ;
void deleteEntry () ;


int main ()
{
    int restart, userOption, otherOption, check, findUser;
    char userName [15];
    
    do{
    userOption = printInfoRecieveOption ();
    if(userOption == 1)
       {
          insertEntry ();
          printf("Contact Added Successfuly!\n\n\n");
       }
    else if(userOption == 2)
       {
          printf("Lookup A Contact\n");
          printf("___________________\n");
          printf("Please Enter The Last Name Of The Contact You Are Trying To Find\n");
          scanf("%s", &userName);
          getchar () ;
          clearScreen () ;
          printf("Contact To Find: %s\n", userName);
          printf("Is This Correct?\n");
          printf("(1) Yes\n");
          printf("(2) No\n");
          scanf("%i", &otherOption);
          getchar () ;
          clearScreen () ;
          if(otherOption > 2 || otherOption < 1)
            check = 3;
          else if(otherOption == 1 || otherOption == 2)
            check = 1;
          while(check == 3)
               {
          printf("Contact To Find: %s\n", userName);
          printf("Is This Correct?\n");
          printf("(1) Yes\n");
          printf("(2) No\n");
          scanf("%i", &otherOption);
          getchar () ;
          clearScreen () ;
          if(otherOption > 2 || otherOption < 1)
            check = 3;
          else if(otherOption == 1 || otherOption == 2)
            check = 1;
              }
                      
           findEntry (userName) ;
       }
    else if(userOption == 3)
       {
          deleteEntry () ;
       }
    else if(userOption == 4)
       {
          printAll ();
       }
    }  while(userOption != 5);
    if(userOption == 5)
    {
      clearScreen () ;
      printf("Goodbye!\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
      system("pause");
      return 0;
    }
    
}


void deleteEntry ()
{
   struct Node *curr = Head;
   char name [15], decide;
   int Decide;
   printf("Last Name To Delete\n");
   scanf("%s", &name);
   getchar ();
   while(curr != NULL)
      {
         if(curr->lastName == name)
           {
              printf("First Name: %s\n", curr->firstName);
              printf("Last Name: %s\n", curr->lastName);
              printf("Phone Number: %s\n", curr->Number);
              printf("Is This The Person You Would Like To Delete ? <Y/N>\n");
              scanf("%c", &decide);
              getchar ();
              
              if(decide == 'y' || decide == 'Y')
              Decide = 1;
              
              if(Decide == 1)
                free(curr);
           }
         curr = curr->next;
      }
}


void findEntry (char name [])
{
    struct Node *current = Head;
    char Name [15];
    int find = 0;

	if (current == NULL)
	{
		printf("----------------------------------------\n");
        printf("There Are No Contacts In The Phonebook\n");
        printf("----------------------------------------\n");
	}
	else
	{
		while (current != NULL)
		{
            strncpy(Name,current->lastName , sizeof(current->lastName));
            if(name == Name)
            {
            find = 1;
            }
			current = current ->next;
		}
	}

	if(find == 1)
    printf("Contact Was Found\n");
	else if(find != 1)
	printf("Contact Was Not Found\n");
}







void printAll ()
{
     	struct Node *current = Head;

	if (current == NULL)
	{
		printf("----------------------------------------\n");
        printf("There Are No Contacts In The Phonebook\n");
        printf("----------------------------------------\n");
	}
	else
	{
		while (current != NULL)
		{
            printf("| First Name: %s\n", current->firstName);
			printf("| Last Name: %s\n", current->lastName);
			printf("| Phone Number: %s\n\n\n", current->Number);
			current = current ->next;
		}
	}

	printf("\n");
     
}






void insertEntry ()
{
     char first [15], last [15], number [15];
     int option1, option2, check;
     
     do{   
     printf("Add A Contact\n");
     printf("_________________\n");
     printf("Please Enter Contacts First Name : ");
           scanf("%s", &first);
           getchar ();
           printf("\n");
     printf("Please Enter Contacts Last Name : ");
           scanf("%s", &last);
           getchar ();
           printf("\n");
     printf("Please Enter Contacts Phone Number (XXX-XXX-XXXX) : ");
           scanf("%s", &number);
           getchar ();
           clearScreen () ;
     printf("The Following Entry Will Be Added :\n");
            printf("First Name: %s\n", first);
            printf("Last Name: %s\n", last);
            printf("Phone Number: %s\n", number);
            printf("________________________\n");
            printf("Add This To The Phonebook ? \n");
            printf("( 1 ) Yes\n");
            printf("( 2 ) No\n");
            scanf("%i", &option1);
            getchar () ;
     clearScreen () ;
     if(option1 == 1 || option1 == 2)
     check = 2;
     else if(option1 > 2 || option1 < 1)
     check = 3;
     while(check == 3)
     {
        printf("ERROR: Please Use Either 1 For Yes or 2 For No\n");
        printf("First Name: %s\n", first);
        printf("Last Name: %s\n", last);
        printf("Phone Number: %s\n", number);
        printf("________________________\n");
        printf("Add This To The Phonebook ? \n");
        printf("( 1 ) Yes\n");
        printf("( 2 ) No\n");
        scanf("%i", &option1);
        getchar () ;
        clearScreen ();
        if(option1< 1 || option1 > 3)
        check = 3;
        else if(option1 == 1 || option1 == 2)
        check = 1; 
     }
} while(option1 == 2);
//---------------------------------------------------------------------------
    
     	struct Node *temp;
	temp = (struct Node *) malloc (sizeof(struct Node));

	if (temp != NULL)
	{
		strncpy(temp->firstName, first, sizeof(temp->firstName));
		strncpy(temp->lastName, last, sizeof(temp->lastName));
		strncpy(temp->Number, number, sizeof(temp->Number));

		if (Head == NULL)
		{
			Head = temp;
			Head -> next = NULL;
		}
		else
		{
			temp->next = Head;
			Head = temp;
		}
	}
}






int printInfoRecieveOption ()
{
    int restart;
    printf("1. Add A Contact\n");
    printf("2. Lookup A Contact\n");
    printf("3. Delete A Contact\n");
    printf("4. Display The Entire Phonebook\n");
    printf("5. Exit The Program\n");
    printf("_____________________________________\n");
    printf("What Would You Like To Do ?\n");
    scanf("%i", &restart);
    getchar () ;
    clearScreen () ;
    while(restart > 5 || restart <1)
    {
       printf("PLEASE USE THE NUMBERS 1 - 5\n");
       printf("1. Add A Contact\n");
       printf("2. Lookup A Contact\n");
       printf("3. Delete A Contact\n");
       printf("4. Display The Entire Phonebook\n");
       printf("5. Exit The Program\n");
       printf("_____________________________________\n");
       printf("What Would You Like To Do ?\n");
       scanf("%i", &restart);
       getchar () ;
       clearScreen () ;
    }
    
    return restart;
}


void clearScreen ()
{
    printf("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");     
}

[Disch]

why they are not working correctly that would be wonderful!

"Not working" is not enough information. In what way are they not working?

What do you expect them to do?
What are they actually doing?

[Schwagmister]

Well basically I cannot get the delete function to delete the node with the same string as one entered by the user. Like "last name of the person you want to delete" and it would find the node with that last name, and delete it. And the search function is like the delete function, except it would search a person by their last name instead.

[Disch]

in your delete function:

              if(Decide == 1)
                free(curr);  //<- freeing here
           }
         curr = curr->next;  // <- can't use curr->next here
      }

you can't use curr->next after you free curr. curr will no longer exist.

You'll also need to adjust the pointers in the nodes so that the deleted node is removed from the list.

Say you have 4 nodes: A->B->C->D. And let's say you want to delete the C node. Not only will you need to free the C node, but you will also need to change the B node so that it points to D as its next node.

You want this as an end result: A->B->D
But with what you're doing, you have A->B->X D (B points to 'X', a deleted node, and D is lost/leaked because nothing points to it any more -- the only node that did point to it, C, no longer exists)

[Schwagmister]

Thank You Disch for that, I ended up having to use strcmp in order to successfuly compare the string values, I wasn't doing this before. Then, I used your advice and got it working flawlessly, thank you!