nptr

    A pointer to the character string to be converted to an __int64.

 endptr

    The address of an object where the function can store a pointer
    to the first unrecognized character encountered in the conversion
    process (that is, the character that follows the last character
    in the string being converted). If endptr is a NULL pointer, the
    address of the first unrecognized character is not retained.

 base

    The value, 2 through 36, to use as the base for the conversion.