Reading Struct Strings with Wrong Scanf

Question

Good guys, I am developing a C code that performs data registration in files. However, I have a problem in the function register, which you will see below among the codes.

Struct of the client:

typedef struct
{
        int idCliente;
        char nome[NOME_TAM_MAX];
        char CPF[16];
        char endereco[ENDERECO_TAM_MAX];    
}Cliente;

Macros:

#define NOME_TAM_MAX 51
#define ENDERECO_TAM_MAX 101

Function register:

void cadastrarCliente (void)
{
        Cliente *newCliente = (Cliente *) malloc(sizeof(Cliente));
        if (!newCliente)
        {
                printf("ERRO DE MEMORIA!!!\n");
                exit(-1);
        }
        else
        {
                printf("\n--- PRENCHA OS DADOS DE CADASTRO DO CLIENTE ---\n\n");
                printf("Digite o ID do cliente: ");
                scanf(" %d", &newCliente->idCliente);
                printf("Digite o nome do cliente: ");
                scanf(" %s", newCliente->nome);
                printf("Digite o CPF do cliente: ");
                scanf(" %s", newCliente->CPF);
                printf("Digite o endereco do cliente: ");
                scanf(" %s", newCliente->endereco);

                stream = fopen("cliente.txt", "w+b"); // stream é global
                if (!stream)
                {
                        fputs("ERRO AO TENTAR LER ARQUIVO!!!\n", stderr);
                        exit(-1);
                }
                else
                {
                        fwrite(newCliente, sizeof(Cliente), 1, stream);
                        fclose(stream);
                }
        }

        return;
}

The error is as follows, after typing the client name and hit enter, all other attributes are skipped (showing only the contents of the printf) and the function comes to an end. I inverted the fields, putting the CPF first and then address, after reading the CPF, everything happens successful, but the error repeats when reading the address as well.

Answer 1

I would like to begin by reiterating what I have already said:

It is worth remembering that scanf("%s reads only one word, leaving the rest in the input stream. If you want to read an entire line, switch to scanf("%[^\n]

However, this is the generic example. Looking at your particular case, you get an integer read before, so you’re going to get a line break for reading after the first number, which is going to be the one that gets caught right after you do scanf("%[^\n]. The solution is simply to consume this break with a small space:

scanf(" %[^\n]",
//     ^--aqui

Taking this into account could rewrite your reading code so:

printf("Digite o ID do cliente: ");
scanf("%d", &newCliente->idCliente);
printf("Digite o nome do cliente: ");
scanf(" %[^\n]", newCliente->nome); //mais que uma palavra
printf("Digite o CPF do cliente: ");
scanf(" %s", newCliente->CPF); //uma palavra
printf("Digite o endereco do cliente: ");
scanf(" %[^\n]", newCliente->endereco); //mais que uma palavra

See this example working on Ideone

Another alternative would be to read with fgets that would even be safer, but that has its implications. One of them would be that the fgets leaves the line break read inside the string. In this case I did not suggest it because when using fgets as a general rule it is more appropriate to take all readings with fgets and not interspersed with scanf, which can complicate a little.

Here is another answer I gave that details the reading with fgets: problem-with-gets-e-fgets

Answer 2

Try using scanf(" n %s"), because if not it will read only one string and leave the others behind. And if your name to insert has spaces scanf does not crease, because it closes the reading in the first space or bar 0, if this is your problem try using fgets.

Answer 3

Good evening Yuri, I tested your code and apparently managed to solve the problem as follows:

printf("\n--- PRENCHA OS DADOS DE CADASTRO DO CLIENTE ---\n\n");
    printf("Digite o ID do cliente: ");
    scanf(" %d", &newCliente->idCliente);

    fflush(stdin);

    printf("Digite o nome do cliente: ");
    fgets(newCliente->nome,51,stdin);

    fflush(stdin);

    printf("Digite o CPF do cliente: ");
    fgets(newCliente->CPF,16,stdin);

    fflush(stdin);

    printf("Digite o endereco do cliente: ");
    fgets(newCliente->endereco,101,stdin);

I used the fflush(stdin) to clear the buffer, avoiding skipping the fields that come after, in addition it was possible to capture the strings by keyboard using the fgets()