Problem with chained list in C

Question

I am doing a college job where basically the Program should be done in C language using chained lists and have 3 options:

1. Add music (beginning, middle or end of list) with name, band and duration;
2. Option to display the playlist;
3. Quit the program.

I created the code below, but when I add a new song, the pointer is pointing to itself, rather than pointing to the new element. And when I list the songs, it happens that it displays a list where all the songs in the list are equal to the last song added.

Code:

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

int menu();
void Listar();
void InserirInicio(char* nome, char* banda, char* duracao);

struct Musica {
    char* nome;
    char* banda;
    char* duracao;
    Musica *prox;
} *Head;

int main() {
    int op;
    char nome[100], banda[100], duracao[10];

    while (1) {
    op = menu();
    switch (op) {
    case 1: //inserir no inicio da lista
        printf("Nome da musica: ");
        fflush(stdin);
        fgets(nome, 100, stdin);
        printf("Banda: ");
        fflush(stdin);
        fgets(banda, 100, stdin);
        printf("Duracao da musica: ");
        fflush(stdin);
        fgets(duracao, 10, stdin);
        InserirInicio(nome, banda, duracao);
        break;
    case 2: //Listar todas as musicas
        Listar();
        break;
    case 3: //sair do programa
        return 0;
    default:
        printf("Invalido\n");
    }
}

return 0;
system("pause");
}

int menu() {
    int opcao, c;
    system("Cls");

    printf("1. Adicionar nova musica\n");
    printf("2. Exibir todas as musicas\n");
    printf("3. Sair\n\n");
    printf("Digite sua escolha: ");

    scanf_s("%d", &opcao);
    while ((c = getchar()) != '\n' && c != EOF) {}

    system("Cls");
    return opcao;
}

void Listar() {
    Musica *ElementoVarredura;
    ElementoVarredura = (struct Musica *)malloc(sizeof(struct Musica));

    ElementoVarredura = Head;
    if (ElementoVarredura == NULL) {
        return;
    }

    int contador = 1;

    while (ElementoVarredura != NULL) {
        printf("%d.\n", contador);
        printf("Nome: %s", ElementoVarredura->nome);
        printf("Artista: %s", ElementoVarredura->banda);
        printf("Duracao: %s", ElementoVarredura->duracao);
        ElementoVarredura = ElementoVarredura->prox;
        contador++;
        printf("\n------------------------------------\n");
    }
    printf("\n");
    system("pause");
    return;
}

void InserirInicio(char* nome, char* banda, char* duracao)
{
    Musica *NovoElemento;
    NovoElemento = (struct Musica *)malloc(sizeof(struct Musica));

    NovoElemento->nome = nome;
    NovoElemento->banda = banda;
    NovoElemento->duracao = duracao;
    NovoElemento->prox = NULL;


    if (Head == NULL)
    {
        Head = NovoElemento;
    }
    else
    {
        NovoElemento->prox = Head;
        Head = NovoElemento;
    }
}

What’s wrong with it?

Answer 1

The problem is not that the pointer of your structure is pointing to the structure itself, the problem is that the attributes nome, banda and duracao are pointers, and the pointer of all structures are pointing to the same memory address, so when you change the value at that address with fgets(nome, 100, stdin) for example, this reflects on all structures.

Try moving the declaration of these variables to the same function you create the instance of the structure, this way you will create new references to each structure:

void InserirInicio()
{
    char *nome = (char *)malloc(sizeof(char) * 100);
    char *banda = (char *)malloc(sizeof(char) * 100);
    char *duracao = (char *)malloc(sizeof(char) * 10);
    struct Musica *NovoElemento = (struct Musica *)malloc(sizeof(struct Musica));

    printf("Nome da musica: ");
    fflush(stdin);
    fgets(nome, 100, stdin);
    printf("Banda: ");
    fflush(stdin);
    fgets(banda, 100, stdin);
    printf("Duracao da musica: ");
    fflush(stdin);
    fgets(duracao, 10, stdin);

    NovoElemento->nome = nome;
    NovoElemento->banda = banda;
    NovoElemento->duracao = duracao;
    NovoElemento->prox = NULL;

    if (Head == NULL)
    {
        Head = NovoElemento;
    }
    else
    {
        NovoElemento->prox = Head;
        Head = NovoElemento;
    }
}