我尝试在 Ubuntu 中编译 c++。我在 Gedit 中编写代码,这是一个简单的 hello world 项目。我进入终端运行它,然后gcc helloworld.cc
弹出以下消息:
/tmp/ccy83619.o: In function `main':
helloworld.cc:(.text+0xa): undefined reference to `std::cout'
helloworld.cc:(.text+0xf): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
/tmp/ccy83619.o: In function `__static_initialization_and_destruction_0(int, int)':
helloworld.cc:(.text+0x3d): undefined reference to `std::ios_base::Init::Init()'
helloworld.cc:(.text+0x4c): undefined reference to `std::ios_base::Init::~Init()'
collect2: error: ld returned 1 exit status
这是什么意思?我下一步该怎么做?
答案1
C++ 程序需要与 C++ 标准库链接。尽管你可以手动链接标准库,即gcc -o hello hello.cpp -lstdc++
,通常不这样做。相反,您应该使用g++
代替gcc
,它会libstdc++
自动链接。
例如给定
$ cat hello.cpp
#include <iostream>
int main(void) { std::cout << "Hello world" << std::endl; return 0; }
然后
$ gcc -o hello hello.cpp
/tmp/ccty9cjF.o: In function `main':
hello.cpp:(.text+0xa): undefined reference to `std::cout'
hello.cpp:(.text+0xf): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
hello.cpp:(.text+0x14): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
hello.cpp:(.text+0x1c): undefined reference to `std::ostream::operator<<(std::ostream& (*)(std::ostream&))'
/tmp/ccty9cjF.o: In function `__static_initialization_and_destruction_0(int, int)':
hello.cpp:(.text+0x4a): undefined reference to `std::ios_base::Init::Init()'
hello.cpp:(.text+0x59): undefined reference to `std::ios_base::Init::~Init()'
collect2: error: ld returned 1 exit status
然而
g++ -o hello hello.cpp
$ ./hello
Hello world