GCC 链接器找不到标准库?
我一直在用 XCode 开发一个学校项目.最终产品必须以源代码和 makefile 的形式提交，所以我编写了一个 makefile 并开始编译，以确保我有一个工作副本.这是我的生成文件:
I've been developing a school project in XCode. The final product has to be submitted in source code with a makefile, so I wrote a makefile and to start compiling that way, to make sure I had a working copy. Here's my makefile:
all: main.o StackList.o world.o Farm.o
gcc main.o StackList.o world.o Farm.o -g -o Project1
main.o:
gcc -g -c main.cpp
StackList.o:
gcc -g -c Stacklist.cpp
world.cpp:
gcc -g -c world.cpp
Farm.cpp:
gcc -g -c Farm.cpp
clean:
rm *.o Project1
编译每个目标文件都可以正常工作，但是当它到达全部"链接步骤时，它似乎不知道标准库.从cin"到basic_string"再到operator new"，我收到未定义符号"错误.
Compiling each of the object files works fine, but when it gets to "all," the linking step, it appears to not be aware of the standard library. I get "undefined symbols" error for everythin from "cin", to "basic_string", to "operator new".
我的印象是这些事情不需要直接指出，事实上过去也不需要这样做.
I was under the impression that these things didn't need to be indicated directly, and in fact have not needed to do so in the past.
知道会发生什么吗?
如果有帮助，这里是(非常长的)错误消息的开头:
If it helps, here's the start of the (very long) error message:
Undefined symbols for architecture x86_64:
"std::cin", referenced from:
_main in main.o
"std::cout", referenced from:
_main in main.o
Farm::print(int) in Farm.o
"std::basic_ostream<char, std::char_traits<char> >& std::operator<< <char, std::char_traits<char>, std::allocator<char> >(std::basic_ostream<char, std::char_traits<char> >&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)", referenced from:
_main in main.o
"std::ios_base::Init::Init()", referenced from:
__static_initialization_and_destruction_0(int, int)in main.o
__static_initialization_and_destruction_0(int, int)in StackList.o
__static_initialization_and_destruction_0(int, int)in world.o
__static_initialization_and_destruction_0(int, int)in Farm.o
"std::ios_base::Init::~Init()", referenced from:
___tcf_0 in main.o
___tcf_0 in StackList.o
___tcf_0 in world.o
___tcf_0 in Farm.o
"operator new(unsigned long)", referenced from:
doStackSearch(std::basic_istream<char, std::char_traits<char> >*, std::list<Farm*, std::allocator<Farm*> >*&)in world.o
推荐答案
要链接C++代码，需要使用g++命令，而不是gcc命令.
To link C++ code, you need to use the g++ command, not the gcc command.
编译时，gcc 命令知道它正在编译 C++ 代码，因为 .cpp 后缀(但最好使用 g++ 命令).
When compiling, the gcc command knows that it's compiling C++ code because of the .cpp suffix (but it's a good idea to use the g++ command anyway).
链接时，gcc 命令只会看到一堆.o 文件.g++ 命令与 gcc 命令的不同之处在于它知道在哪里可以找到 C++ 特定的库.
When linking, the gcc command just sees a bunch of .o files. The g++ command differs from the gcc command in that it knows where to find the C++-specific libraries.
(事实上，gcc 这个名称既指通常用于编译 C 代码的命令，也指整个GNU 编译器集合"，这一事实可能有点令人困惑.)
(The fact that the name gcc refers both to the command, which is usually used to compile C code, and the "GNU Compiler Collection" as a whole, can be a little confusing.)
相关文章