This question already has an answer here: 'float' vs. 'double' precision 6 answers Those are the total number of "significant figures" if you will, counting from left to right, regardless of where the decimal point is. Beyond those numbers of digits, accuracy is not preserved. The counts you listed are for the base 10 representation. There are macros for the num
这个问题在这里已经有了答案： '浮动'与'双'精度6个答案 如果您愿意，从左到右数，无论小数点在哪里，这些都是“有效数字”的总数。 除了这些数字之外，精度不会被保留。 您列出的计数是针对基数10的表示。 每种类型支持的小数位数都有宏。 gcc文档解释了它们是什么以及它们的含义： FLT_DIG 这是浮点数据类型的精度的小数位数。 从技术上讲，如果p和b分别是表示的精度和基数（分别），那么小数精
What would be the most efficient way to compare two double or two float values? Simply doing this is not correct: bool CompareDoubles1 (double A, double B) { return A == B; } But something like: bool CompareDoubles2 (double A, double B) { diff = A - B; return (diff < EPSILON) && (-diff < EPSILON); } Seems to waste processing. Does anyone know a smarter float compar
什么是比较两个double float值或两个float值的最有效方法？ 简单地做这件事是不正确的： bool CompareDoubles1 (double A, double B) { return A == B; } 但是像这样： bool CompareDoubles2 (double A, double B) { diff = A - B; return (diff < EPSILON) && (-diff < EPSILON); } 似乎浪费处理。 有谁知道更聪明的浮点比较器？ 使用任何其他建议时要格外小心。 这一切都取决于上下文。
This is a little bit difficult because I don't even know if my C++ is well implemented. I want to call a function from Unity3D which I pass some parameters such float *points and my C++ writes in that pointer. Well, starting from the C++ part, I've written: main_function.cpp this is my main function in C++ which works perfectly as binary, for example. #include "main_function.h" ex
这有点困难，因为我甚至不知道我的C ++是否被很好地实现。 我想从Unity3D调用一个函数，我传递了一些参数，如float *points和我的C ++写入该指针。 那么，从C ++部分开始，我写道： main_function.cpp这是我在C ++中的主要功能，例如，它完全像二进制一样工作。 #include "main_function.h" extern "C" void getPoints (uchar *data, float *points, int rows, int cols, const char *trackername) { //load detector
I've set a catch point in gdb to catch exceptions with catch throw . How do I remove it without restarting gdb session? Neither delete nor clear seem to be helpful here. It turned out I tried to delete it wrongly with delete throw . (gdb) info breakpoints Num Type Disp Enb Address What 2 breakpoint keep y 0x063e3255 exception throw delete 2 did the trick.
我给自己定一个支撑点gdb赶上例外catch throw 。 如何在不重新启动gdb会话的情况下将其删除？ 这里delete或clear似乎都没有帮助。 事实证明，我试图用delete throw错误地删除它。 (gdb) info breakpoints Num Type Disp Enb Address What 2 breakpoint keep y 0x063e3255 exception throw delete 2的窍门。
I have the following code (simplified), which compiles fine in gcc, but gives an error in VS: // main.cpp #include "test.h" int main() { return 0; } // test.h #pragma once class Test { static const int TEST = 3; }; // test.cpp #include "test.h" const int Test::TEST; Error: main.obj : error LNK2005: "private: static int const Test::TEST" (?TEST@Test@@0HB) already defined in test.obj Is i
我有下面的代码（简化），它在gcc中编译得很好，但在VS中给出错误： // main.cpp #include "test.h" int main() { return 0; } // test.h #pragma once class Test { static const int TEST = 3; }; // test.cpp #include "test.h" const int Test::TEST; 错误： main.obj : error LNK2005: "private: static int const Test::TEST" (?TEST@Test@@0HB) already defined in test.obj 是VS错误还是gcc错误地允许我明确定
Is there a class that does garbage collection for C++. I was thinking something like: class A : public GarbageCollected<A> { void kill() { GarbageCollected<A>.set_cleanup_flag(); } ... private: GarbageCollectedPointer<B> b_pointer; // Somehow we follow GarbageCollectedPointer<B> b_pointer2; // these pointers. }; class B { ... }; class GarbageContain
有没有一个类为C ++做垃圾回收？ 我在想像这样： class A : public GarbageCollected<A> { void kill() { GarbageCollected<A>.set_cleanup_flag(); } ... private: GarbageCollectedPointer<B> b_pointer; // Somehow we follow GarbageCollectedPointer<B> b_pointer2; // these pointers. }; class B { ... }; class GarbageContainer { ... }; int main() { GarbageCon
What free and commercial garbage collection libraries are available for C++, and what are the pros and cons of each? I am interested in hard-won lessons from actual use in the field, not marketing or promotional blurb. There is no need to elaborate on the usual trade offs associated with automatic garbage collection, but please do mention the algorithms used (reference counting, mark and swee
什么免费和商业垃圾收集库可用于C ++，每个垃圾收集库有哪些优缺点？ 我对这个领域的实际使用的经验教训感兴趣，而不是市场营销或促销活动。 没有必要详细说明与自动垃圾收集相关的常规权衡，但请提及所使用的算法（引用计数，标记和扫描，增量等）并简要总结其后果。 过去我曾经使用Boehm收藏家，取得了很好的成绩。 它是开源的，可用于商业软件。 它是一位保守的收藏家，并且由垃圾收集技术领域最重要的研究人员之一
How do I trick linux into thinking a memory read/write was successful? I am writing a C++ library such that all reads/writes are redirected and handled transparently to the end user. Anytime a variable is written or read from, the library will need to catch that request and shoot it off to a hardware simulation which will handle the data from there. Note that my library is platform dependent
如何欺骗Linux认为内存读/写成功？ 我正在编写一个C ++库，以便所有读/写操作都可以重定向到最终用户并进行透明处理。 任何时候写入或读取变量时，库都需要捕获该请求，并将其发送到可处理来自那里的数据的硬件模拟。 请注意，我的图书馆依赖于以下平台： Linux ubuntu 3.16.0-39-generic＃53〜14.04.1 -Ubuntu SMP x86_64 GNU / Linux gcc（Ubuntu 4.8.2-19ubuntu1）4.8.2 当前方法：捕获SIGSEGV并增加REG_RIP 我目
In C++11 standard the machine model changed from a single thread machine to a multi threaded machine. Does this mean that the typical static int x; void func() { x = 0; while (x == 0) {} } static int x; void func() { x = 0; while (x == 0) {} } static int x; void func() { x = 0; while (x == 0) {} } example of optimized out read will no longer happen in C++11? EDIT: for those who don't kno
在C ++ 11标准中，机器型号从单线程机器变为多线程机器。 这是否意味着典型的static int x; void func() { x = 0; while (x == 0) {} } static int x; void func() { x = 0; while (x == 0) {} } static int x; void func() { x = 0; while (x == 0) {} }优化出读的例子将不再发生在C ++ 11中？ 编辑：对于那些不知道这个例子的人（我很惊讶），请阅读：https：//en.wikipedia.org/wiki/Volatile_variable EDIT2：OK，我
My simple code like this: #include <iostream> #include <atomic> #include <memory> int main(void) { std::shared_ptr<int> p = std::make_shared<int>(5); std::cout << std::boolalpha << std::atomic_is_lock_free(&p) << std::endl; return 0; } But compile error: a.cpp: In function 'int main()': a.cpp:7:60: error: no matching fun
我这样简单的代码： #include <iostream> #include <atomic> #include <memory> int main(void) { std::shared_ptr<int> p = std::make_shared<int>(5); std::cout << std::boolalpha << std::atomic_is_lock_free(&p) << std::endl; return 0; } 但编译错误： a.cpp：在函数'int main（）'中：a.cpp：7：60：错误：没有匹配函数调用'atomic_