printf impl using c++ templates

#include <iostream>
#include <iomanip>
#include <type_traits>

void _pf_seek_direct_out(const char *&format)
{
    for (; *format != '\0'; ++format) {
        if (*format == '%') {
            switch (*++format) {
            case '%':
                std::cout << '%';
                break;

            default:
                return;
            }
        } else {
            std::cout << *format;
        }
    }
}

void _pf_output_format(const char *&format)
{
    /* Flags */
    bool stop = false;
    do {
        switch (*format) {
        case '#':
            std::cout << std::showbase;
            break;

        case '0':
            std::cout << std::setfill('0');
            break;

        case '-':
            std::cout << std::left;
            std::cout << std::setfill(' ');
            break;

        case ' ':
            std::cout << std::setfill(' ');
            break;

        case '+':
            std::cout << std::showpos;
            break;

        default:
            stop = true;
            break;
        }
        format++;
    } while (!stop);

    format--;

    /* Field width */
    int num = 0;
    while ('0' <= *format && *format <= '9') {
        num *= 10;
        num += *format++ - '0';
    }
    if (num)
        std::cout << std::setw(num);

    /* Precision */
    if (*format == '.') {
        int num = 0;
        while ('0' <= *format && *format <= '9') {
            num *= 10;
            num += *format++ - '0';
        }
        std::cout << std::setprecision(num);
    }
}

template<typename T, typename ...Ts>
void printf(const char *format, T arg, Ts... args)
{
    static_assert(std::is_integral<T>::value, "Implementation for integral types");

    // Seek normal text
    _pf_seek_direct_out(format);

    // Apply output format settings
    _pf_output_format(format);

    // Conversion specifiers
    switch (*format++) {
    case 'd':
    case 'i':
        std::cout << std::dec;
        break;

    case 'O':
        std::cout << std::uppercase;
        /* Fall-through */
    case 'o':
        std::cout << std::oct;
        break;

    case 'X':
        std::cout << std::uppercase;
        /* Fall-through */
    case 'x':
        std::cout << std::hex;
        break;

    default:
        ; /* Errör :c */
    }

    std::cout << arg;

    printf(format, args...);
}

int main()
{
    printf("Das ist der %d. Test mit %X Format Anweisungen drinne: %08x, %-10d!\n", 123, 4, 0xff, 12345);

    return 0;
}