Binary Search Tree project

[Vasillis13]

So i have this university project and one of my tasks is to make a Binary Search Tree that does some operations !

Write a program in C that will process data for student IT graduates. The data should be loaded from a text file containing the following information for each student: Student Identity, Student Name, Surname, Grade in the Data Structure course.
The application initially reads the file and creates a BST in which each node maintains a record of the file. The BST is arranged in terms of student identity and implemented with dynamic memory management. After the BST has been created, the application displays a menu with the following options


1) Imaging the BST with in-order intersection
2) Search the student based on his / her identity
3) Modification of the student's registered data based on his / her identity
4) Delete a student record based on his / her identity
5) Exit the application


Specifically from what you see in my code I have trouble importing the data in BST correctly, I can not find a way to create a function that will process the data as well as I can not find a function that will delete a record from BST . Finally, the program crashes when I ask her to search for a student on the basis of his identity.


Here is the code :

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#define MAXLEN 20

struct record
{
    char id[10];
    char firstName[20];
    char lastName[20];
    char score[10];
};

struct node
{
    char *value;
    struct node *leftptr;
    struct node *rightptr;
};

typedef int (*Compare)(const char *, const char *);


void insert(char* key, struct node** leaf, Compare cmp)
{
    int res;
    if( *leaf == NULL )
    {
        *leaf = (struct node*) malloc( sizeof( struct node ) );
        (*leaf)->value = malloc( strlen (key) +1 );
        strcpy ((*leaf)->value, key);
        (*leaf)->leftptr = NULL;
        (*leaf)->rightptr = NULL;
    }
    else
    {
        res = cmp (key, (*leaf)->value);
        if( res < 0)
        {
            insert( key, &(*leaf)->leftptr, cmp);
        }
        else if( res > 0)
        {
            insert( key, &(*leaf)->rightptr, cmp);
        }
        else
        {
            printf ("Key '%s' already in tree\n", key);

        }
    }
}


int CmpStr(const char *a, const char *b)
{
    return (strcmp (a, b));
}

void in_order(struct node *root)
{
    if( root != NULL )
    {
        in_order(root->leftptr);
        printf("   %s\n", root->value);
        in_order(root->rightptr);
    }
}

void search(char* key, struct node* leaf, Compare cmp)
{
    int res;
    if( leaf != NULL )
    {
        res = cmp(key, leaf->value);
        if( res < 0)
        {
            search( key, leaf->leftptr, cmp);
        }
        else if( res > 0)
        {
            search( key, leaf->rightptr, cmp);

        }
        else
        {
            printf("\n'%s' found!\n", key);

        }
    }
    else
    {
        printf("\nNot in tree\n");
    }
    return;
}

char *input()
{
    static char line[MAXLEN+1];
    printf("Please enter a string : ");
    fgets(line, sizeof line, stdin);
    return (strtok(line, "\n" ));
}

void menu()
{
    printf("Please select one of the following options : a) Display students in order\tb) Search a student via it's id\tc)Edit students info\td)Delete a student\td)EXIT\n");
}

int main()
{
    FILE *fileptr;
    struct node *p_root=NULL;

    int i=0,idx=0;


    fileptr=fopen("students.txt","r");
    struct record *pinakas;
    pinakas=(struct record *)malloc(17*sizeof(struct record));

    if(fileptr)
    {
        while(!feof(fileptr))
        {
            fscanf(fileptr,"%[^ ] %[^ ] %[^ ] %[^ \n]\n", pinakas[idx].id, pinakas[idx].firstName, pinakas[idx].lastName, pinakas[idx].score);
            insert(pinakas[idx].id, &p_root, (Compare)CmpStr);
            idx++;
        }
    }


    char *searchID;
    char option;
    option='x';

    while(option!='e')
    {
        menu();

        option=getch();

        if(option=='a')
        {
            in_order(p_root);
        }
        else if(option=='b')
        {
            searchID=input();
            search(searchID, &p_root, (Compare)CmpStr);
        }
        else if(option=='c')
        {
            printf("Edit student info\n");
        }
        else if(option=='d')
        {
            printf("Delete student from archives\n");
        }
        else if(option=='e')
        {
            exit(1);
        }
    }

    fclose(fileptr);
    free(pinakas);

    return 0;
}

The .txt file is like this:

AB123456 ANNA SMITH 10.0
AB234567 BILL WHITE 3.0
AB345678 GEORGE REDD 7.0
...

[Salem]

struct node
{
    char *value;

Why char *value, and not struct record *value?

[Click_here]

Read this
or this
You shouldn't use feof to control your while loop

[Lookchup]

a binary search tree (BST), which may sometimes also be called an ordered or sorted binary tree, is a node-based binary tree data structure which has the following properties: The left subtree of a node contains only nodes with keys less than the node's key.