blocks|key|1312014|text|这两条错误消息非常清楚。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1312015|第一个说明你不能用非常量值初始化一个变量。|1312016|虽然log(M_PI)确实是常量，但编译器不能将其视为常量，因为它不知道函数log()是否总是返回相同的结果。它确实存在，但编译器必须假定它不存在，因此是“非常量”。|offset|length|style|CODE|1312017|第二个示例说明您尝试在此处调用的函数gamma尚未定义。|1312018|因此，它假定它是一个extern+int+gamma()。由于不清楚此函数是在何处声明的，因此您至少应该包含包含其原型的适当头文件。|1312019|entityMap^0|0|0|2|9|12|5|0|I|5|0|A|I|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|R|8|@$F|S|G|T|H|I]|$F|U|G|V|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|W|8|@$F|X|G|Y|H|I]]|9|@]|A|$]]|$1|L|3|M|5|6|7|Z|8|@$F|10|G|11|H|I]]|9|@]|A|$]]|$1|N|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|O|$]]

The two error messages are quite clear.

The first one says that you cannot initialize a variable with a non-constant value.

while <code>log(M_PI)</code> is indeed constant, the compiler cannot treat it as such, because it doesn't know if the function <code>log()</code> always returns the same result. It does, but the compiler must assume it doesn't, hence "non-constant".

The second one says that the function <code>gamma</code> you try to call here is not defined.

Hence, it assumes it is an <code>extern int gamma()</code>. As it is unclear where this function is declared, you should at least include the appropriate header file containing its prototype.

blocks|key|1312045|text|这一行是导致第一个错误的原因：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1312046|const+double+log_pi+=+log(M_PI);|code-block|syntax|javascript|1312047|表达式log(M_PI)不是常量，不能在初始化中使用。或者改用以下代码，或者在main函数中移动定义并删除const|offset|length|style|CODE|1312048|const+double+log_pi+=+1.1447298858494002;|1312049|第二个错误是因为编译器找不到函数gamma。它似乎没有在您的math.h中定义。如果你没有收到链接器错误，我建议你添加：|1312050|double+gamma+(double);|1312051|正确的做法是找到要包含的正确的头文件。This+question可能会带来一些启示。|1312052|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/18116376/what-is-the-definition-for-gammadouble-x-and-why-is-it-different-on-two-gcc-ve^0|0|0|3|9|13|4|1H|5|0|0|G|5|U|6|0|0|J|D|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|14|8|@$I|15|J|16|K|L]|$I|17|J|18|K|L]|$I|19|J|1A|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|1C|8|@$I|1D|J|1E|K|L]|$I|1F|J|1G|K|L]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|1H|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1I|8|@]|9|@$I|1J|J|1K|1|1L]]|A|$]]|$1|U|3|-4|5|6|7|1M|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]]]

This line is the cause of your first error:

<pre><code>const double log_pi = log(M_PI);
</code></pre>

The expression <code>log(M_PI)</code> is not constant and cannot be used in the initialization. Either use the following instead, or move the definition inside your <code>main</code> function and remove the <code>const</code>:

<pre><code>const double log_pi = 1.1447298858494002;
</code></pre>

The second error is because the compiler cannot find the function <code>gamma</code>. It seems that it is not defined in your <code>math.h</code>. If you're not getting linker errors, I suggest that you add:

<pre><code>double gamma (double);
</code></pre>

The right thing to do would be to find the proper header file to include. <a href="https://stackoverflow.com/questions/18116376/what-is-the-definition-for-gammadouble-x-and-why-is-it-different-on-two-gcc-ve">This question</a> could shed some light.

blocks|key|5096336|text|log(M_PI)不是常量表达式，它是一个常量限定对象，在C语言术语中不是常量。为此，您需要声明一个命名常量，您应该使用#define或enum，但不能使用const限定符。const+double+类型的变量在C中不是常量。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|BOLD|entityRanges|data|5096337|#define+log_pi+log(M_PI)|code-block|syntax|javascript|5096338|entityMap^0|0|9|1O|7|1W|4|26|5|2F|C|2F|C|2S|7|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]|$9|Y|A|Z|B|D]|$9|10|A|11|B|D]]|E|@]|F|$]]|$1|G|3|H|5|I|7|12|8|@]|E|@]|F|$J|K]]|$1|L|3|-4|5|6|7|13|8|@]|E|@]|F|$]]]|M|$]]

<code>log(M_PI)</code> is not a constant expression, its a constant qualified object which is not constants in C language terminology. For this you need to declare a named constant you should use either <code>#define</code> or <code>enum</code>, but not <code>const</code> qualifier. Variables of <code>const double</code> type are not constants in C. 

<pre><code>#define log_pi log(M_PI)
</code></pre>

blocks|key|1252115|text|静态常量需要在编译时初始化，你在那里放了一个函数调用。像gcc这样的高级编译器可以在编译时计算出类似这样的东西，并且只会警告非法构造，而不会出错。你的显然无法做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1252116|另一件事是，gamma()不是一个标准的libmath函数，它们是一些Unix非标准的东西，你可以在BSD和Linux上找到，但在你的Windows上不会(按照你的路径名)。不管怎样，它已经被弃用了，并且有tgamma()和lgamma()，它们是在C99中标准化的。|offset|length|style|CODE|1252117|entityMap^0|0|6|7|2V|8|34|8|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]|$D|N|E|O|F|G]|$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|R|8|@]|9|@]|A|$]]]|I|$]]

A static const needs to be initialized at compile time, you put a function call there. Advanced compilers such as gcc can compute something like this at compile time anyway and will just warn about the illegal construct instead of erroring out. Yours apparently is not capable of this.

The other thing is that <code>gamma()</code> is not a standard libmath function, they are some Unix non-standard thing you would find on BSDs and Linux but not (going by your path names) on your Windows. It is deprecated anyway and there are <code>tgamma()</code> and <code>lgamma()</code> which are standardized in C99.

I am trying to use an open source R tree however I get errors. I have spent several hours to fix it but could not. Please help.
The part of the code is as below:

<pre><code>#include &lt;stdio.h&gt;
#include &lt;math.h&gt;


#ifndef M_PI
# define M_PI 3.1415926535
#endif
#ifndef ABS
# define ABS(a) ((a) &gt; 0 ? (a) : -(a))
#endif

#define EP .0000000001

const double log_pi = log(M_PI);



double sphere_volume(double dimension)
{
 double log_gamma, log_volume;
 log_gamma = gamma(dimension/2.0 + 1);
 log_volume = dimension/2.0 * log_pi - log_gamma;
 return exp(log_volume);
}
</code></pre>

I get the following errors:
1>c:\users\user\desktop\r\gammavol.c(14): error C2099: initializer is not a constant
1>c:\users\user\desktop\r\gammavol.c(21): warning C4013: 'gamma' undefined; assuming extern returning int

line 14 is const double log_pi = log(M_PI);
line 21 is log_gamma = gamma(dimension/2.0 + 1);

thanks in advance

error C2099: initializer is not a constant & warning C4013: 'gamma' undefined; assuming extern returning int

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

我正在尝试使用一个开源的R树，但是我得到了错误。我花了几个小时来修复它，但没能解决。请帮帮忙。代码部分如下：#include <stdio.h>#include <math.h>#ifndef M_PI# define M_PI 3.1415926535#endif#ifndef ABS# define ABS...

问错误C2099:初始值设定项不是常量&警告C4013：'gamma‘未定义；假定外部返回整数
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问错误C2099:初始值设定项不是常量&警告C4013：'gamma‘未定义；假定外部返回整数EN