为什么stddef.h不在/ usr / include中？ [英] Why is stddef.h not in /usr/include?

问题描述

我编译了gnu标准库，并将其安装在 $ GLIBC_INST 中。

现在，我尝试编译非常简单的程序（仅使用一个#include： #include ）：

  gcc --nostdinc -I $ GLIBC_INST / include foo.c 
  

编译（预处理器？）告诉我，它没有找到 stddef.h 。

事实上， $ GLIBC_INST / include 中没有一个（ / usr / include ）。不过，我在 /usr/lib/gcc/x86_64-unknown-linux-gnu/5.3.0/include 中找到 stddef.h code>。

为什么该文件不在 / usr / include 下？我认为它属于标准C库，应该安装在 $ GLIBC_INST / include 中。

我怎么能编译我的 foo.c 与新安装的标准库时，它似乎不带有 stddef.h ？

编辑：澄清

我觉得这个问题的标题是不是最佳的。正如一些答案指出的那样，不需要 stddef.h 位于 / usr / include （或 $ GLIBC_INST / include ，就此而言）。我明白这一点。

但我想知道如何在我想使用 $ GLIBC_INST 时继续操作。我似乎很明白（虽然我可能在这里是错误的），我需要调用与 - nostdinc gcc为了不使用系统安装的头文件。
这意味着我使用 -I $ GLIB_INST / include 。我清楚这一点。

然而，我还不清楚的是：当我还添加 -I / usr / lib / gcc / x86 .... / include ，我怎么能确定我确实拥有新编译的glibc的最新头文件？

解决方案

这是因为 / usr / include 下的文件是C库提供的常见头文件，例如 glibc ，而 / usr / lib / gcc 中的文件是特定于该特定编译器的文件。通常每个编译器都有自己的 stddef.h 不同的实现，但它们将使用相同的 stdio.h 当链接到安装的C库时。

I have compiled the gnu standard library and installed it in $GLIBC_INST.

Now, I try to compile a very simple programm (using only one #include : #include <stdio.h>):

gcc --nostdinc -I$GLIBC_INST/include foo.c

The compilation (preprocessor?) tells me, that it doesn't find stddef.h.

And indeed, there is none in $GLIBC_INST/include (nor is there one in /usr/include). However, I found a stddef.h in /usr/lib/gcc/x86_64-unknown-linux-gnu/5.3.0/include.

Why is that file not under /usr/include? I thought it belonged to the standard c library and should be installed in $GLIBC_INST/include.

How can I compile my foo.c with the newly installed standard library when it doesn't seem to come with a stddef.h?

Edit: Clarification

I feel that the title of this question is not optimal. As has been pointed out by some answers, there is not a requirement for stddef.h to be in /usr/include (or $GLIBC_INST/include, for that matter). I do understand that.

But I am wondering how I can proceed when I want to use $GLIBC_INST. It seems obvious to me (although I might be wrong here) that I need to invoke gcc with --nostdinc in order to not use the system installed header files. This entails that I use -I$GLIB_INST/include. This is clear to me.

Yet, what remains unclear to me is: when I also add -I/usr/lib/gcc/x86..../include, how can I be sure that I do have in fact the newest header files for the freshly compiled glibc?

解决方案

That's because files under /usr/include are common headers that provided by the C library, for example, glibc, while the files at /usr/lib/gcc are specific for that particular compiler. It is common that each compiler has their own different implementation of stddef.h, but they will use the same stdio.h when links to the installed C library.

这篇关于为什么stddef.h不在/ usr / include中？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！