c++ - 由于嵌套的匿名 block ，代码无法编译？

Question

(摘自 Accelerated C++)

为什么下面的代码不起作用:

#include <iostream>
#include <string>

int main() {
    {
        const std::string s = "a string";
        std::cout << s << std::endl;

        {
            const std::string s = "another string";
            std::cout << s << std::endl;
        }
    }
}

我不允许在 C++ 中嵌套匿名 block 吗？尝试编译源代码时，gcc 给出了以下错误(我无法理解):

hello: In function `_start':(.text+0x0): multiple definition of`_start'/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.text+0x0):first defined herehello:(.rodata+0x0): multipledefinition of `_fp_hw'/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.rodata+0x0):first defined here hello: In function`_fini': (.fini+0x0): multipledefinition of `_fini'/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crti.o:(.fini+0x0):first defined herehello:(.rodata+0x4): multipledefinition of `_IO_stdin_used'/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.rodata.cst4+0x0):first defined here hello: In function`__data_start': (.data+0x0): multipledefinition of `__data_start'/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.data+0x0):first defined here hello: In function`__data_start': (.data+0x4): multipledefinition of `__dso_handle'/usr/lib/gcc/i486-linux-gnu/4.4.3/crtbegin.o:(.data+0x0):first defined here hello: In function`_init': (.init+0x0): multipledefinition of `_init'/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crti.o:(.init+0x0):first defined here /tmp/cchh83A6.o: Infunction `main':hello.cpp:(.text+0x0): multipledefinition of `main'hello:(.text+0xb4): first defined here/usr/lib/gcc/i486-linux-gnu/4.4.3/crtend.o:(.dtors+0x0):multiple definition of `__DTOR_END__'hello:(.dtors+0x4): first defined here/usr/bin/ld: warning: Cannot create.eh_frame_hdr section, --eh-frame-hdrignored. /usr/bin/ld: error inhello(.eh_frame); no .eh_frame_hdrtable will be created. collect2: ldreturned 1 exit status

Answer 1

该代码工作正常。看这里Your code compiled (你的环境有问题)