How does a chained list work in C?

Question

I’m doing a job for college and I still don’t fully understand the logic behind a chained list in C.

I need to log in, name and value in a record, of which I created a struct (set of variables); I created another struct to be my nodes and a third struct to be the chained Ita.

How do these three structs relate to each other and why do they all have pointers to the next? It would not only be necessary for nodes to have pointers to the next?

There is a difference from the traditional examples. In this example, why does the log struct have pointer? It would not be enough to pointer the node struct?

typedef struct registro_st{         // sequência de objetos do mesmo tipo
        char login[50];
        char nome[50];
        float valor;
        struct registro *prox;
    } registro;


typedef struct nodo_st{
    registro dado;
    struct nodo *prox;
} nodo;


typedef struct Lista_st{
    nodo *cabeca;
    nodo *cauda;
    int tamanho;
} lista;

Answer 1

I’m no expert, but for me there are unnecessary things there, I think you could simplify for this guy:

typedef struct registro_st{
    char login[50];
    char nome[50];
    float valor;
    struct registro *prox;
} registro;

typedef struct Lista_st{
    registro *cabeca;
    registro *cauda;
    int tamanho;
} lista;

On the chained list, basically each "object" in the list will point to the next element of the list, if any. - This is simply chained up. If it is double chained, each "object" instead of just pointing to the next, will also point to the previous one.

And in the case of your code, you will have the pointers at the beginning and end of the list. (head and tail)

I hope I’ve been of some help!