仅使用 g++ 有效，但不能使用“g++ -c"；和 ld [英] Using only g++ works, but not "g++ -c" and ld

问题描述

我在 main.cpp 中有以下源代码:

I have the following source code in main.cpp:

#include <iostream>
#include <iomanip>

int main() {
    std::cout << "Hi" << std::endl;
    return 0;
}

使用此命令有效，并创建可执行文件:

Using this command works, and creates the executable file:

g++ -o main main.cpp

但是这个命令不起作用:

But this commands don't work:

g++ -c main.cpp
ld -o main main.o

第二个错误:

ld: warning: cannot find entry symbol _start; defaulting to 00000000004000e8
main.o: In function `main':
main.cpp:(.text+0xa): undefined reference to `std::cout'
main.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*)'
main.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> >&)'
main.cpp:(.text+0x1c): undefined reference to `std::ostream::operator<<(std::ostream& (*)(std::ostream&))'
main.o: In function `__static_initialization_and_destruction_0(int, int)':
main.cpp:(.text+0x4a): undefined reference to `std::ios_base::Init::Init()'
main.cpp:(.text+0x4f): undefined reference to `std::ios_base::Init::~Init()'
main.cpp:(.text+0x54): undefined reference to `__dso_handle'
main.cpp:(.text+0x61): undefined reference to `__cxa_atexit'

推荐答案

我想如果你直接使用 ld 默认不包含 C++ 库.您也可以使用 g++ 进行链接，它会以正确的设置调用 ld.

I think if you use ld directly it does not include the C++ libraries by default. You can use g++ to do the linking as well, it will call ld with the correct settings.

g++ -c main.cpp
g++ -o main main.o

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