编译检测powf等 [英] compile detection of powf, etc

问题描述

是否有一种标准方法使用预处理器来检测给定的C / b
编译器/库环境是否提供了C99< math.h>浮点

函数如：


float powf（float x，float y）;

float sqrtf（float x） ;

等


所以我们可以提供这些原型是否通过我们的


" xtra_math.h"文件


注意某些C环境不完整，可能会定义C90标志，但是

仍然提供这些功能。所以我想我们需要检查每个

的功能。


寻找任何建议


谢谢

Is there a standard way using the preprocessor to detect if a given C
compiler/library environment provides the C99 <math.h> floating point
functions such as:

float powf(float x, float y);
float sqrtf(float x);
etc

so we could "provide" these prototypes or not via our

"xtra_math.h" file

Note some C environments are incomplete and may define the C90 flag but
still provide these functions. So I think we need to check each
function.

looking for any suggestions

thanks

推荐答案

在文章< 11 ********************** @ g47g2000cwa.googlegroups .com>，

Marco< pr ********** @ yahoo.com>写道：

In article <11**********************@g47g2000cwa.googlegroups .com>,
Marco <pr**********@yahoo.com> wrote:

是否有一种标准的方法使用预处理器来检测给定的C / /编译器/库环境是否提供C99< math.h>浮点
函数如：
float powf（float x，float y）;
float sqrtf（float x）;
注意某些C环境不完整，可能会定义C90标志但
仍然提供这些功能。所以我认为我们需要检查每个功能。


C90没有定义任何功能测试预处理器变量，

所以任何这样的宏由C90之间的环境提供

根据定义，C99是非标准的。


如果你需要能够确定

特定例程的存在与否，我建议你考虑使用像

automake这样的东西。


所以我们可以提供这些原型是否通过我们的
" xtra_math.h"文件

Is there a standard way using the preprocessor to detect if a given C
compiler/library environment provides the C99 <math.h> floating point
functions such as: float powf(float x, float y);
float sqrtf(float x); Note some C environments are incomplete and may define the C90 flag but
still provide these functions. So I think we need to check each
function.
C90 does not define any feature-test preprocessor variables,
so any such macro provided by an environment intermediate between C90
and C99 is, by definition, non-standard.

If you need to be able to determine the presence or absence of
particular routines, I suggest you consider using something like
"automake".

so we could "provide" these prototypes or not via our
"xtra_math.h" file

暗示商业产品;如果是这样，那么如果你看看

automake，请确保你阅读随附的许可证。

-

一切都是虚荣心。 - 传道书

That hints at a commercial product; if so then if you do look at
automake, ensure that you read the accompanying licenses.
--
All is vanity. -- Ecclesiastes

Marco写于01/30/06 10:21，：

Marco wrote On 01/30/06 10:21,:

是否有一种标准方法使用预处理器来检测给定的C / /编译器/库环境是否提供C99< math.h>浮点
函数如：

float powf（float x，float y）;
float sqrtf（float x）;
等

" xtra_math.h"文件

请注意，某些C环境不完整，可能会定义C90标志但
仍然提供这些功能。所以我认为我们需要检查每个功能。

Is there a standard way using the preprocessor to detect if a given C
compiler/library environment provides the C99 <math.h> floating point
functions such as:

float powf(float x, float y);
float sqrtf(float x);
etc

so we could "provide" these prototypes or not via our

"xtra_math.h" file

Note some C environments are incomplete and may define the C90 flag but
still provide these functions. So I think we need to check each
function.

`＃if __STDC_VERSION__> = 199901L''测试是否

实施声称符合C99;如果确实如此，你正在寻找的

函数是否存在。


我能想到没有便携的方法来判断这些是否

函数在早期实现中作为扩展存在。

您可以使用`#ifdef powf'来检查屏蔽功能。宏

并假设如果定义了

宏，则存在相应的函数，但该函数可能也存在而没有

一个屏蔽宏。您可能只需要定制您的

" xtra_math.h"标题为你关心的每个实现，

可能使用autoconf等半自动工具。


-
呃********* @ sun.com

`#if __STDC_VERSION__ >= 199901L'' tests whether the
implementation claims to conform to C99; if it does, the
functions you''re looking for are present.

I can think of no portable way to tell whether these
functions exist as extensions in earlier implementations.
You could use `#ifdef powf'' to check for a "masking" macro
and assume that the corresponding function exists if the
macro is defined, but the function might also exist without
a masking macro. You may simply need to tailor your
"xtra_math.h" header to each implementation you care about,
possibly with a semi-automated tool like autoconf.

--
Er*********@sun.com

2006-01-30，Marco< pr ********** @ yahoo.com>写道：

On 2006-01-30, Marco <pr**********@yahoo.com> wrote:

是否有一种标准的方法使用预处理器来检测给定的C / /编译器/库环境是否提供C99< math.h>浮点
函数如：

float powf（float x，float y）;
float sqrtf（float x）;
等

" xtra_math.h"文件

请注意，某些C环境不完整，可能会定义C90标志但
仍然提供这些功能。所以我认为我们需要检查每个功能。

寻找任何建议

感谢

Is there a standard way using the preprocessor to detect if a given C
compiler/library environment provides the C99 <math.h> floating point
functions such as:

float powf(float x, float y);
float sqrtf(float x);
etc

so we could "provide" these prototypes or not via our

"xtra_math.h" file

Note some C environments are incomplete and may define the C90 flag but
still provide these functions. So I think we need to check each
function.

looking for any suggestions

thanks

（半offtopic）

一种方式[这是高度系统特定的 - 基本上只有unix，并且可能

即使按POSIX标准也不保证]将是在静态库中提供

函数并在libm之后链接它。如果链接编辑器

在libm中找到它，它就不会从你的库中找到它。

静态库

(semi-offtopic)
One way [this is highly system-specific - basically unix-only, and may
not be guaranteed even by the POSIX standard] would be to provide the
functions in a static library and link it after libm. If the link editor
finds it in libm, it won''t take the one from your library.
static library

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