Not sure how long to alpha conversion on a PC has much to do with the theme of this message board, namely 8052's and their derivatives, but taken from Microsoft's online help, the methods can include any of the following:

errno_t _ltoa_s(
    long value,
    char *str,
    size_t sizeOfstr,
    int radix 
);
errno_t _ltow_s(
    long value,
    wchar_t *str,
    size_t sizeOfstr,
    int radix 
);
template <size_t size>
errno_t _ltoa_s(
    long value,
    char (&str)[size],
    int radix 
); // C++ only
template <size_t size>
errno_t _ltow_s(
    long value,
    wchar_t (&str)[size],
    int radix 
); // C++ only