未定义对函数的引用 [英] undefined refrence to a function

问题描述

我一直在尝试编译一些原本应该工作的源代码，并且会出现一些编译错误。错误与

sqrt（），log（）和round（）函数有关。我有math.h包含并制作

确定它在路径中。我已经在论坛上看到，有些人已经通过告诉GCC链接数学库来解决这个问题，如果它没有通过

默认完成。


所以，使用gcc -lm帮助解决了定义

前两个函数的问题。但是，round（）仍未定义：undefined

引用round（）


我发现的另一个建议是检查是否编译器

正在使用C99 VS C90库。在使用GCC 4.0.2时，我遇到了这些问题，这是非常困难的。


您对此有何看法？为什么这是个问题？至于我理解为
，在C99中定义了round（），gcc 4.0.2应该有C99库附带的
。


谢谢

Hi,

I have been trying to compile some source code that is supposed to be
working and getting some compilation errors. The errors are with
sqrt(), log() and round() functions. I have math.h included and made
sure it''s in the path. I have read on the forums that some have fixed
the problem by telling GCC to link math libraries if it''s not done by
default.

So, using gcc -lm helped to resolve the problems with defining the
first two functions. However, round() is still undefined: "undefined
reference to round()"

Another suggestion that I have found is to check whether the compiler
is using C99 VS C90 library. This is quite stange that I have faced
these problems while using GCC 4.0.2.

What do you think about this? Why is this a problem? As far as I
understood, round() has been defined in C99 and gcc 4.0.2 should have
come with C99 libraries.

Thank you

推荐答案

bobrics写道：

bobrics wrote:

sqrt（），log（）和round（）函数有关。我有math.h包含并确保它在路上。我已经在论坛上看到有人已经通过告诉GCC链接数学库来解决这个问题，如果它不是默认的那样。

那么，使用gcc - lm帮助解决了定义前两个函数的问题。但是，round（）仍未定义：undefined
对round（）的引用

我发现的另一个建议是检查编译器是否正在使用C99 VS C90库。我在使用GCC 4.0.2时遇到了这些问题，这是非常困难的。

你怎么看待这个？为什么这是个问题？据我所知，round（）已在C99中定义，gcc 4.0.2应该有C99库。

Hi,

I have been trying to compile some source code that is supposed to be
working and getting some compilation errors. The errors are with
sqrt(), log() and round() functions. I have math.h included and made
sure it''s in the path. I have read on the forums that some have fixed
the problem by telling GCC to link math libraries if it''s not done by
default.

So, using gcc -lm helped to resolve the problems with defining the
first two functions. However, round() is still undefined: "undefined
reference to round()"

Another suggestion that I have found is to check whether the compiler
is using C99 VS C90 library. This is quite stange that I have faced
these problems while using GCC 4.0.2.

What do you think about this? Why is this a problem? As far as I
understood, round() has been defined in C99 and gcc 4.0.2 should have
come with C99 libraries.

尝试gcc列表圆形应该在那里。


-

Ian Collins。

Try a gcc list, round should be there.

--
Ian Collins.

Ian Collins写道：

Ian Collins wrote:

bobrics写道：

bobrics wrote:

我一直在尝试编译一些应该是
工作并获得一些编译错误。错误与
sqrt（），log（）和round（）函数有关。我有math.h包含并确保它在路上。我已经在论坛上看到有人已经通过告诉GCC链接数学库来解决这个问题，如果它不是默认的那样。

那么，使用gcc - lm帮助解决了定义前两个函数的问题。但是，round（）仍未定义：undefined
对round（）的引用

我发现的另一个建议是检查编译器是否正在使用C99 VS C90库。我在使用GCC 4.0.2时遇到了这些问题，这是非常困难的。

你怎么看待这个？为什么这是个问题？据我所知，round（）已在C99中定义，gcc 4.0.2应该有C99库。

Hi,

I have been trying to compile some source code that is supposed to be
working and getting some compilation errors. The errors are with
sqrt(), log() and round() functions. I have math.h included and made
sure it''s in the path. I have read on the forums that some have fixed
the problem by telling GCC to link math libraries if it''s not done by
default.

So, using gcc -lm helped to resolve the problems with defining the
first two functions. However, round() is still undefined: "undefined
reference to round()"

Another suggestion that I have found is to check whether the compiler
is using C99 VS C90 library. This is quite stange that I have faced
these problems while using GCC 4.0.2.

What do you think about this? Why is this a problem? As far as I
understood, round() has been defined in C99 and gcc 4.0.2 should have
come with C99 libraries.

尝试gcc列表圆形应该在那里。

Try a gcc list, round should be there.

或者你的平台列表，我在Solaris上没有gcc这个问题。


-

Ian Collins。

Or a list for your platform, I don''t have this problem with gcc on Solaris.

--
Ian Collins.

gcc列表是什么意思？


方式，我尝试使用命令提示符编译文件

而不是像以前那样做Eclipse构建，我刚刚得到

后面的错误。否则它有效。我认为-lm实际上已经修复了问题：

What do you mean by gcc list?

By the way, I have tried compiling the file using just command prompt
and not Eclipse build as I was doing before and I''ve just got the
following errors. Otherwise it works. I think -lm actually has fixed
the problem:

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