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


typedef struct record
{   
    char name[20];
    char surname[20];
    char telephone[20];

}Record;

typedef struct node
{
    Record data;
    struct node *next;
}Node;

Node *head = NULL;

void addRecord(Record s)
{
    Node *newNode;
    Node *n;

    newNode = (Node*)malloc(sizeof(Node));
    newNode->data = s;
    newNode->next = NULL;

    if (head == NULL)
    {
        // The linked list is empty
        head = newNode;
    }
    else
    {
        // Traverse the whole list until we arrive at the last node
        n = head;
        while (n->next != NULL)
        {
            n = n->next;
    }
        n->next = newNode;
    }
}

Record enterRecordDetails()
{
    Record aRecord;
    int len;
    int valid = 0;
    int valid2 = 0;
    printf("ENTER THE FOLLOWING RECORD DETAILS:\n");

    printf("   NAME      : ");
    gets(aRecord.name);
    printf("   SURNAME   : ");
    gets(aRecord.surname);  
    do {
        valid = 0;
        valid2 = 0;
        printf("  TELEPHONE NO. (8 digits): ");
        gets(aRecord.telephone);
        len = strlen(aRecord.telephone);
        for (int i = 0; i < len; i++)
        {
            if (!isdigit(aRecord.telephone[i])) {
                printf("You enterred an invalid number\n");
                valid = 1; break;
            }
        }
        Node *p = head;         
            while (p != NULL)
            {
                Node *next = p->next;
                for (; next; p = next, next = next->next) {
                    if (strcmp(p->data.telephone, aRecord.telephone) == 0)
                    {
                        valid2 = 1; break;
                    }
                }
                if(p = NULL)break;
            }

    } while((valid == 1) || (len != 8) || (valid2 == 1));
    getchar();
    fflush(stdin);
    return aRecord;
}


int main(void)
{
    char menuOption;

    do
    {
        system("cls");
        printf("~~~ MAIN MENU ~~~\n");
        printf("1. Add Telephone Record\n");
        printf("2. Delete Telephone Record\n");
        printf("3. Search\n");
        printf("4. Display All Records\n");
        printf("5. Exit\n\n");
        menuOption = getchar();
        fflush(stdin);
        switch (menuOption)
     {
    case '1':
        addRecordToList();
        break;
    case '4':
        displayList();
        break;
    }

} while (menuOption != '5');

getchar();
return 0;

}

Al agregar un estudiante, la computadora le pide al usuario que ingrese el apellido en lugar del nombre. ¿Por qué el programa omite 'Nombre'? Se muestra 'Nombre', sin embargo, se espera que el usuario escriba el apellido en su lugar.