C++ “编译错误”；“未定义的符号”；关于osx

我正在osx上试用一个非常简单的cpp程序，只是为了让自己熟悉osx平台，所以遇到任何错误消息我都感到非常惊讶

代码如下：

#include <iostream> 
using namespace std; 
int main() { 
  cout << "Hello, world!" << endl; 
  return 0; 
}

然后我得到了“未定义符号”的信息：

Undefined symbols:
  "std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)", referenced from:
      _main in ccA9oElQ.o
  "std::ios_base::Init::Init()", referenced from:
      __static_initialization_and_destruction_0(int, int)in ccA9oElQ.o
  "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::size() const", referenced from:
      std::__verify_grouping(char const*, unsigned long, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)in ccA9oElQ.o
  "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::operator[](unsigned long) const", referenced from:
      std::__verify_grouping(char const*, unsigned long, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)in ccA9oElQ.o
      std::__verify_grouping(char const*, unsigned long, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)in ccA9oElQ.o
      std::__verify_grouping(char const*, unsigned long, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)in ccA9oElQ.o
  "___gxx_personality_v0", referenced from:
      std::__verify_grouping(char const*, unsigned long, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)in ccA9oElQ.o
      _main in ccA9oElQ.o
      ___tcf_0 in ccA9oElQ.o
      unsigned long const& std::min<unsigned long>(unsigned long const&, unsigned long const&)in ccA9oElQ.o
      __static_initialization_and_destruction_0(int, int)in ccA9oElQ.o
      global constructors keyed to mainin ccA9oElQ.o
      CIE in ccA9oElQ.o
  "std::ios_base::Init::~Init()", referenced from:
      ___tcf_0 in ccA9oElQ.o
  "std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)", referenced from:
      _main in ccA9oElQ.o
  "std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))", referenced from:
      _main in ccA9oElQ.o
  "std::cout", referenced from:
      _main in ccA9oElQ.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

系统信息

$ uname -a
Darwin mbp002.local 10.7.0 Darwin Kernel Version 10.7.0: Sat Jan 29 15:17:16 PST 2011; root:xnu-1504.9.37~1/RELEASE_I386 i386

---

<>使用<代码> g++< /COD>而不是<代码> GCC >因为编译C++程序：

g++ -Wall hello.cpp -o hello

或者，使用

clang++

，因为苹果已经有一段时间没有更新GCC了，而且他们也不太可能更新它：

clang++ -Wall hello.cpp -o hello

用g运行它++

g++ -Wall hello.cpp -o hello

---

如果使用GCC，默认情况下，C++库没有链接。

@ KIILL不，不是！！（但是是的，是的）@bevariable:谢谢你的回答！当我尝试“clang++”时，出现了“未找到命令”错误。虽然我可以调用clang，但它给了我一大堆错误信息。（我想这是gcc和g++之间的问题？！）@Anthony你没有

/usr/bin/clang++

？在XCODEL 4中没有安装命令行实用程序，可能XCODE 3没有安装代码> CLAN++/CODE >，因为Clang中的C++支持是相当新的。如果我没记错的话，命令行实用程序是可选安装。或者，从macports获取gcc4.6。只是更新：在最新版本的xcode中，建议通过xcrun调用构建工具。因此，对于clang++来说，它是

xRun clang++选项

clang++ -Wall hello.cpp -o hello

g++ -Wall hello.cpp -o hello