Print and store spanish characters (á, é, í, ñ...) in cmd

Question

I'm using Microsoft Windows 10 with mingw-w64 (gcc version 8.1.0, x86_64-posix-sjlj-rev0, Built by MinGW-W64 project) with cmd. When I try to print or store and then print a Spanish character on the Windows console, it shows an error. For example I tried to execute this program:

#include <stdio.h>

int main(void) {
    char c[20];
    printf("pía\n");
    scanf("%s", c);
    printf("%s", c);
}

If I introduce some Spanish characters the returned sentence is OK but the printed one at the beginning shows an error:

pía
laíóñaú
laíóñaú

Some solutions suggest putting setlocale() function but the results are the same. Other solution is put the UTF-8 unicode compatibility on region settings:

But now the error is the opposite, the printed one is OK but when I introduce a strange character the console doesn't show it:

pía
lía
l

It is a bit frustrating since all the solutions I have seen are solved with the above or by setting setlocale(), but none of them work for me and I don't know why.

EDIT

As Mofi say in comments I try to use SetConsoleCP() and SetConsoleOutputCP() to change the code page of the console. Without fully understanding how these functions work, with the same code as above, I ran several examples with wrong results:

pía                       | p├¡a                    | p├¡a                  | pía
lía                       | lía                     | lía                   | lía
l                         | l                       | lía                   | la
input: 65001 output 65001 | input: 65001 output 850 | input: 850 output 850 | input: 850 output 65001

How I don't fully understand this functions I don't know why in the last example, the console don't show the accented stored character but in the printed one it does and in the example above the opposite happens.

Answer 1

I played around with this for a while and the only thing that worked was using _setmode() to set the stdin and stdout to take in wide characters, and then working with wchar_t instead of char to store the text. This code works as intended on my machine:

#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void) {
    _setmode(_fileno(stdin), _O_WTEXT);
    _setmode(_fileno(stdout), _O_WTEXT);
    wchar_t c[20];
    wprintf(L"pía\n");
    wscanf(L"%ls", c);
    wprintf(L"%ls", c);
}

EDITED: I changed the parameter of _setmode from _O_U16TEXT to _O_WTEXT to avoid implementation issues resulting from how the length of wchar_t is either 2 or 4 bytes based on the compiler.