Question

#include <iostream>
#include <cstdlib>
#include <ctime>    
using namespace std;


int main()
{
    srand(time(NULL));
    cout << rand() << endl ; 
    return 0; 
}

错误消息：

Undefined symbols for architecture x86_64:
  "std::__1::locale::use_facet(std::__1::locale::id&) const", referenced from:
      std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in test-c5b4b5.o
  "std::__1::ios_base::getloc() const", referenced from:
      std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in test-c5b4b5.o
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >::put(char)", referenced from:
      std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in test-c5b4b5.o
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >::flush()", referenced from:
      std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in test-c5b4b5.o
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(int)", referenced from:
      _main in test-c5b4b5.o
  "std::__1::cout", referenced from:
      _main in test-c5b4b5.o
  "std::__1::ctype<char>::id", referenced from:
      std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in test-c5b4b5.o
  "std::__1::locale::~locale()", referenced from:
      std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in test-c5b4b5.o
  "std::terminate()", referenced from:
      ___clang_call_terminate in test-c5b4b5.o
  "___cxa_begin_catch", referenced from:
      ___clang_call_terminate in test-c5b4b5.o
  "___gxx_personality_v0", referenced from:
      std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in test-c5b4b5.o
      Dwarf Exception Unwind Info (__eh_frame) in test-c5b4b5.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Answer 1

BLUF：使用g++，而不是gcc。

这是链接器错误的示例。您的程序编译得很好 - 例如您可以在错误消息中看到对中间*.o文件的引用 - 但是它遇到了将事物链接在一起以生成可执行文件的问题 - 链接器无法找到程序所需的许多功能（例如， iostream库中使用的一些东西。

原因是因为您用于构建程序的命令以使链接器尝试将其构建为 C 程序的方式执行 - 特别是，它仅链接到< em> C 标准库，而不是 C ++ 标准库，这就是它无法找到这些东西的原因。

通过将构建命令更改为使链接器意识到它正在构建C ++程序的命令，错误就会消失。

我自己使用gnu编译器集合遇到了这一点 - 虽然gcc足够智能编译一个*.cpp程序作为C ++代码，它仍然试图链接结果作为C程序。因此，您需要使用g++命令来构建C ++程序。

为什么这个简单的c ++代码无法编译？

1 个答案: