Question

出于某种原因，每当我将FLTK目录添加到包含路径时，我都会从 cmath 中收到一堆错误。我使用的是GCC 4.2版。这是一个示例程序和构建输出：

的main.cpp

#include <cmath>

int main()
{
    return 0;
}

**** Build of configuration Debug for project CMath Test ****

make -k all 
Building file: ../main.cpp
Invoking: GCC C++ Compiler
g++ -I/usr/include/FL -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"main.d" -MT"main.d" -o"main.o" "../main.cpp"
In file included from ../main.cpp:1:
/usr/include/c++/4.2/cmath:100: error: ‘::acos’ has not been declared
/usr/include/c++/4.2/cmath:116: error: ‘::asin’ has not been declared
/usr/include/c++/4.2/cmath:132: error: ‘::atan’ has not been declared
/usr/include/c++/4.2/cmath:148: error: ‘::atan2’ has not been declared
/usr/include/c++/4.2/cmath:165: error: ‘::ceil’ has not been declared
/usr/include/c++/4.2/cmath:181: error: ‘::cos’ has not been declared
/usr/include/c++/4.2/cmath:197: error: ‘::cosh’ has not been declared
/usr/include/c++/4.2/cmath:213: error: ‘::exp’ has not been declared
/usr/include/c++/4.2/cmath:229: error: ‘::fabs’ has not been declared
/usr/include/c++/4.2/cmath:245: error: ‘::floor’ has not been declared
/usr/include/c++/4.2/cmath:261: error: ‘::fmod’ has not been declared
/usr/include/c++/4.2/cmath:271: error: ‘::frexp’ has not been declared
/usr/include/c++/4.2/cmath:287: error: ‘::ldexp’ has not been declared
/usr/include/c++/4.2/cmath:303: error: ‘::log’ has not been declared
/usr/include/c++/4.2/cmath:319: error: ‘::log10’ has not been declared
/usr/include/c++/4.2/cmath:335: error: ‘::modf’ has not been declared
/usr/include/c++/4.2/cmath:354: error: ‘::pow’ has not been declared
/usr/include/c++/4.2/cmath:376: error: ‘::sin’ has not been declared
/usr/include/c++/4.2/cmath:392: error: ‘::sinh’ has not been declared
/usr/include/c++/4.2/cmath:408: error: ‘::sqrt’ has not been declared
/usr/include/c++/4.2/cmath:424: error: ‘::tan’ has not been declared
/usr/include/c++/4.2/cmath:440: error: ‘::tanh’ has not been declared
make: *** [main.o] Error 1
make: Target `all' not remade because of errors.
Build complete for project CMath Test

g++ -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.2.3 (Ubuntu 4.2.3-2ubuntu7)

谁能告诉我什么是错的？谢谢！

Answer 1

纯粹的推测，但/usr/include/FL中是否有'math.h'标题？或者cmath包含哪些其他标题？

[...过了一会儿......]

仍在猜测，但鉴于评论“是的，还有 - 发生了什么？”，我将推测/ usr / include中没有'math.h'标题 - 因为如果有GCC（G ++）会通常从与''相同的地方拿起。所以，我会检查已安装的软件 - / usr / include下的标题 - 为了理智。

[......再过一段时间......]

啊，好吧......似乎问题是有两个math.h标题，编译器选错了。

你可以尝试一些技巧。首先，或许是检查FLTK的文档：你应该使用<FL/header.h>还是<header.h>来访问它的标题？如果您应该将该版本与子目录一起使用，则不需要将-I/usr/include/FL添加到编译命令行;对<FL/header.h>的引用将自动处理（通过在扫描/usr/include/FL/header.h时查找/usr/include - 就像在<sys/types.h>下找到/usr/include一样。）

如果这不是答案的一部分，那么您可以尝试使用标志：

-I/usr/include -I/usr/include/FL

这表示在搜索/usr/include之前搜索/usr/include/FL（然后在搜索/usr/include）后再次搜索/usr/include/FL“。这应该解决当前的问题 - 但是它可能会导致任何应该包括/usr/include/FL/math.h的问题。这绝对不如第一个选项那么可靠。

Answer 2

我有类似的问题。这是由于Qt Creator在包含路径中无意中创建了math.h而导致我为隐藏math.h文件的项目创建了一个数学子包。我发现这只是做find / -name math.h。当然可能需要一段时间，但它可以解决所有问题。

Answer 3

Scott，将-lm添加到那里的链接器标记列表中，你会没事的。

Answer 4

我使用Qt Creator 3.3.0并遇到了同样的问题

有趣的是我通过移动线解决了它

#include＆lt; cmath＆gt;

到其他#include

之前的第一行

它解决了我的问题!!!

cmath使用FLTK时出错

4 个答案: