CPF data in a C Struct

Question

Hello. I’m having a problem reading data from a CPF. I tried using int, long int or even a char vector[12]. With char I can keep the CPF’s that contain '0' at the beginning, and with int or long int it does not return correct due to size. I need to sort with this data as well and the order is not correct either. I believe it is due to the type of data that is incorrect.

Answer 1

There are several ways you can store a Cpf in the memory/database.

1. String: use a char[12], or else a char[11] since you know the size. Remember to never use operations that expect a string with null terminator, like strcpy. Use memcpy or even strncpy in place.

2. Array: store each digit in an array. It can be uint8_t[11]. It is similar to using the string option. But you will need to use a loop to do any operation with the digits.

3. Whole: use a single uint64_t. It is the simplest way to operate if you do not need separate digits. To display on the screen use: print("cpf: %011"PRIu64".", cpf); Explaining the format: an integer uint64_t 11 digits in size, filling the missing space with 0. The macro PRIu64 denotes the string used in printf. To the scanf you can use it like this: scanf("%"SCNu64, &cpf);

Any one of the three will do and there are no doubt more. Choose the one that best suits your specific case.

Answer 2

Hello, the main problem of storing number with zero start starts when the number has more than 7 digits, as is the case with the CPF. The compiler believes that when a number has more than 7 digits and starts with zero it is from base 8. Causing some problems for us. The best option is to store the numbers in this case as a string.

For example, to check if the number amount is correct we could do something like:

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


int checkCPF(char* cpf) {
        printf("CPF como string: %s \n", cpf);
        printf("Números do CPF: %lu \n", strlen(cpf));
        if(strlen(cpf)==11) {
            return 1;
        }
        return 0;
}


int main() {
        char* cpfA = "18315228889";
        char* cpfB = "0031522888";

        checkCPF(cpfA);
        checkCPF(cpfB);

        return 0;
}

But this is not very practical if you are going to work with the numbers themselves, perform some kind of validation or take only a part of the number, in this case we can use a CPF structure, you can implement your structure however you want, for example:

typedef struct _CPF{
    unsigned int a;
    unsigned int b;
    unsigned int c;
    unsigned int verificador;
} CPF;

It’s a very simple structure, and you can work with the numbers in isolation. To get the full CPF as a long int you can use a function like:

long int getCPFCompleto(CPF cpf) {
    long int cpfCompleto = 0;
    char buffer[12];
    char* fixEnd;
    sprintf(buffer, "%d%d%d%d", cpf.a, cpf.b, cpf.c, cpf.verificador);
    cpfCompleto = strtol (buffer,&fixEnd,10);
    return cpfCompleto;
}

Of course, if CPF has the first number 0 in any of the elements it can cause problems then it is better to return the value as a string again.

The logic is complete. I will post only the full code commented and hope I can assist you in something.

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

// Nossa estrutura básica para armazenar o CPF
typedef struct _CPF{
    unsigned int a;
    unsigned int b;
    unsigned int c;
    unsigned int verificador;
} CPF;


// Retorna o CPF completo
// É possivel informar se queremos o número formatado ou não
void getCPFCompleto(char* buffer, CPF cpf, int formatado) {
    long int cpfCompleto = 0;

    // Aqui está um ponto fundamental
    // Perceba que informmos %03d informando que esperamos 3 dígitios
    // Caso ele conter menos que 3 digitos ele adiciona zero a esquerda.
    // Execeto no número verificado com 2 dígitos
    if(formatado)
        sprintf(buffer, "%03d.%03d.%03d-%02d", cpf.a, cpf.b, cpf.c, cpf.verificador);
    else
        sprintf(buffer, "%03d%03d%03d%02d", cpf.a, cpf.b, cpf.c, cpf.verificador);
}

// Populamos nossa variavel CPF
void populateCPF(CPF* cpf, char* cpfString, int formatado) {
    if(formatado)
        sscanf(cpfString, "%03u.%03u.%03u-%02u", &cpf->a, &cpf->b, &cpf->c, &cpf->verificador);
    else
        sscanf(cpfString, "%03d%03d%03d%02d", &cpf->a, &cpf->b, &cpf->c, &cpf->verificador);
}



int main() {
    CPF mCPF;
    char* cpfCompleto;

    // Alocamos 15 caso o valor retornado possuir formatação
    cpfCompleto = (char*) malloc(15*sizeof(char));

    // Passamos nossa o ponteiro para nossa variavel CPF
    // O CPF para ser formatado como string
    // E se o número é formatado ou não
    populateCPF(&mCPF, "08315228802", 0);

    // Podemos imprimir os elementos de forma unitaria
    printf("CPF A: %03d\n", mCPF.a);
    printf("CPF B: %03d\n", mCPF.b);
    printf("CPF C: %03d\n", mCPF.c);
    printf("CPF Verificador: %02d\n", mCPF.verificador);


    // Podemos imprimir o número completo utilizando a função
    // getCPFCompleto
    // Informamos um ponteiro para char a variavel com o CPF
    // e se queremos formatada ou não

    getCPFCompleto(cpfCompleto, mCPF, 0);
    printf("O número do CPF completo é: %s \n", cpfCompleto);


    // Vamos liberar a memoria do buffer
    free(cpfCompleto);

    return 0;
};