当我遇到一个绊脚石时,我正在研究 C++0x 中的一些新东西:
#include <list>
#include <cstdio>
using namespace std;
template <typename T,typename F>
void ForEach (list<T> l, F f) {
for (typename list<T>::iterator it=l.begin();it!=l.end();++it)
f(*it);
}
int main() {
int arr[] = {1,2,3,4,5,6};
list<int> l (arr,arr+6);
ForEach(l,[](int x){printf("%d\n",x);});
}
不编译。我收到一大堆 undefined symbol 错误。这是 make
的输出:
i386-apple-darwin9-gcc-4.5.0 -std=c++0x -I/usr/local/include -o func main.cpp
Undefined symbols:
"___cxa_rethrow", referenced from:
std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o
"operator new(unsigned long)", referenced from:
__gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o
"___gxx_personality_v0", referenced from:
___gxx_personality_v0$non_lazy_ptr in ccPxxPwU.o
"___cxa_begin_catch", referenced from:
std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o
"operator delete(void*)", referenced from:
__gnu_cxx::new_allocator<std::_List_node<int> >::deallocate(std::_List_node<int>*, unsigned long) in ccPxxPwU.o
"___cxa_end_catch", referenced from:
std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o
"std::__throw_bad_alloc()", referenced from:
__gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o
"std::_List_node_base::_M_hook(std::_List_node_base*)", referenced from:
void std::list<int, std::allocator<int> >::_M_insert<int const&>(std::_List_iterator<int>, int const&&&) in ccPxxPwU.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
make: *** [func] Error 1
为什么这不起作用?
最佳答案
那些是链接错误。您缺少 C++ 库吗?如果您使用 i386-apple-darwin9-g++-4.5.0
会怎么样?
附言我无法对此进行测试,因为我的 Mac 上有 gcc 4.2.1 (i686-apple-darwin10-gcc-4.2.1) 并得到:
cc1plus: error: unrecognized command line option "-std=c++0x"
关于c++ - C++0x lambda 的 undefined symbol ?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/2665112/