我应该#include使用'htonl'？ [英] What should I #include to use 'htonl'?

问题描述

我想在我的ruby c扩展中使用 htonl 函数，但不想使用随附的任何其他互联网内容。什么是最简约的文件 #include 仍然可移植？查看计算机上的头文件，我可以看到 machine / endian.h 或 sys / _endian.h 会让我使用它们，虽然我不确定这是不是一个好主意。

I want to use the htonl function in my ruby c extension, but don't want to use any of the other internet stuff that comes with it. What would be the most minimalistic file to #include that is still portable? Looking through the header files on my computer, I can see that either machine/endian.h or sys/_endian.h would let me use them, although I am not sure if that is a good idea.

推荐答案

标准标题是：

#include <arpa/inet.h>

您不必担心该标头中定义的其他内容。它不会影响您编译的代码，并且只会对编译时间产生轻微影响。

You don't have to worry about the other stuff defined in that header. It won't affect your compiled code, and should have only a minor effect on compilation time.

编辑：您可以对此进行测试。创建两个文件，htonl_manual.c

You can test this. Create two files, htonl_manual.c

// non-portable, minimalistic header
#include <byteswap.h>
#include <stdio.h>
int main()
{
    int x = 1;
    x = __bswap_32(x);
    printf("%d\n", x);
}

和htonl_include.c：

and htonl_include.c:

// portable
#include <arpa/inet.h>
#include <stdio.h>
int main()
{
    int x = 1;
    x = htonl(x);
    printf("%d\n", x);
}

将它们组装在-O1，然后取差价：

Assemble them at -O1, then take the difference:

gcc htonl_manual.c -o htonl_manual.s -S -O1
gcc htonl_include.c -o htonl_include.s -S -O1
diff htonl_include.s htonl_manual.s

对我而言，唯一的区别是文件名。

For me, the only difference is the filename.

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