utf8_readln.cpp

#include <cstdio>
#include <windows.h>
#define INPUT_MAX 255

void main()
{
    wchar_t wstr[INPUT_MAX];
    char mb_str[INPUT_MAX * 3 + 1];
    unsigned long readln;

    SetConsoleOutputCP(CP_UTF8);
    SetConsoleCP(CP_UTF8);
    
    void *console = GetStdHandle(STD_INPUT_HANDLE);

    ReadConsole(console, wstr, INPUT_MAX, &readln, NULL);

    int size = WideCharToMultiByte(CP_UTF8, 0, wstr, readln, mb_str, sizeof(mb_str), NULL, NULL);
    
    mb_str[size] = 0;

    printf("echo: %s\n", mb_str);

    return;
}