AIX下cpp程序编译出现错误(ios::beg) 谢谢！

richardzhang

ifstream f;
f.seekg(0,ios::beg);
编译出现错误：
The reference to "ios" is ambiguous.
"/usr/vacpp/include/iostream.h", line 78.7: 1540-0425 (I) "ios" is defined on line 78 of "/usr/vacpp/include/iostream.h".
"/usr/vacpp/include/iosfwd", line 330.45: 1540-0425 (I) "std::ios" is defined on line 330 of "/usr/vacpp/include/iosfwd".
make: 1254-004 The error code from the last command is 1.

ifstream f;
f.seekg(0,std::ios::beg);
编译出现错误：
"/usr/vacpp/include/ios", line 146.9: 1540-0300 (S) The "private" member "std::basic_ios<char,std::char_traits<char> >::basic_ios(const _Myt &)" cannot be accessed.
"/usr/vacpp/include/fstream", line 237.15: 1540-0719 (I) The previous message was produced while processing the implicit member function "std::basic_ifstream<char,struct std::char_traits<char> >::basic_ifstream(const basic_ifstream<char,std::char_traits<char> > &)".
请问如何改啊？谢谢！