用用户输入和通过指针访问来填充结构

Question

I´m trying to create a structure populated by the user and accessed through a pointer.

As it stands right now I don´t get compiler errors but it won't take input correctly, I need to input the second variable twice, and the output is garbage.

I´m trying to get pointers and structures down before moving on to linked lists, any help would be appreciated.

//struct date

struct data {    
    int dia;
    int mes;
    int ano;
};

//struct client

struct cliente {        
    char nome[15];
    int num_conta;
    float saldo;
    struct data dia_d_mes;          
};


// function that returns pointer to struct populated by user

struct cliente *input_cliente()
{    
    struct cliente *tipo_cliente, n;        
    SYSTEMTIME st;
    GetSystemTime (&st);

    tipo_cliente = &n;

    printf ("Nome cliente:");   
    gets (tipo_cliente->nome);
    //fflush (stdin);

    printf ("Numero da conta:");
    scanf ("%d ", &tipo_cliente->num_conta);

    printf ("Saldo da conta:");
    scanf ("%f ", &tipo_cliente->saldo);

    tipo_cliente->dia_d_mes.dia = st.wDay;
    tipo_cliente->dia_d_mes.mes = st.wMonth;
    tipo_cliente->dia_d_mes.ano = st.wYear;

    return tipo_cliente;            // return pointer    
}

//print client

void print_cliente(struct cliente *tipo_cliente)
{    
    printf  ("%s", tipo_cliente->nome);
    printf  ("\t%d", tipo_cliente ->num_conta);
    printf  ("\t%.2f", tipo_cliente ->saldo);
    printf  ("\t%d/%d/%d\n", tipo_cliente->dia_d_mes.dia, tipo_cliente->dia_d_mes.mes, tipo_cliente->dia_d_mes.ano);    
}


int main()
{    
    struct cliente *novo;       //declare a new struct pointer
    system ("color 17");
    system ("mode 70,10");

    novo = input_cliente();     //create new client

    system ("cls");

    printf ("Nome \t #conta \t Saldo \tData\n");
    printf ("============================================\n");

    print_cliente (novo);       //print new client    
}

I´ve been playing around with the code and changed the pointer to a normal structure input but keep having one constant problem.
When the second printf is desplayed and the int is entered, it doesn´t move to the next printf the cursor moves to a new line in the command prompt. Any idea would be apreciated, I´ve tryed different things with the pointer and without, but I´m running out of ideas.

// function that returns pointer to struct populated by user

struct cliente input_cliente() { struct cliente tipo_cliente; // initialize struct SYSTEMTIME st; GetSystemTime (&st);

printf ("Nome cliente:");
gets (tipo_cliente.nome);                //accepts this value

printf ("Numero da conta:");
scanf ("%d ", &tipo_cliente.num_conta);  //also accepts this value 
                                           //after pressing enter goes to a empty line
printf ("Saldo da conta:");
scanf ("%f ", &tipo_cliente.saldo);  //the value stored in this variable is the 
                                       // value entered in the previous empty line
tipo_cliente.dia_d_mes.dia = st.wDay;
tipo_cliente.dia_d_mes.mes = st.wMonth;
tipo_cliente.dia_d_mes.ano = st.wYear;

return tipo_cliente;            // return pointer

}

Answer 1

input_cliente returns a pointer to a variable declared within the function. However, once the function ends, the contents of that variable become undefined. You should either return an actual struct cliente (not a pointer) or use malloc to allocate memory for a struct cliente* that will last beyond the function's execution.

Answer 2

Here n is the local variable of the function input_cliente . So the scope of n is limited to the function body. It will be invalid after the function returns.

So you should either allocate it on the free store using malloc :

struct cliente* tipo_cliente = (struct cliente*) malloc(sizeof(struct cliente));

Or let the function have an out parameter:

struct cliente* input_cliente(struct cliente* tipo_cliente)
{
     // fill tipo_cliente here.
}