I found an odd line of code in the REActivityViewController project on GitHub and cannot understand it. It appears to avoid casting the value to the exact class that it is declared as, but I do not know why that would be necessary. I wonder if it is somehow important for inheritance. Can anyone explain why this would be done? __typeof(&*self) __weak weakSelf = self; https://github.com/r
我在GitHub的REActivityViewController项目中发现了一行奇怪的代码，无法理解它。 它似乎避免将价值投射到它声明的确切类别，但我不知道为什么这是必要的。 我怀疑它是否对继承有重要意义。 任何人都可以解释为什么会这样做吗？ __typeof(&*self) __weak weakSelf = self; https://github.com/romaonthego/REActivityViewController/blob/master/REActivityViewController/REPocketActivity.m 通过这样声明，我会更
I am new to using Graphics in Visual C++. I am just trying to make a rectangle filled with a color. Need help to correct this... RECT rect; HDC hdc; hdc=CreateDC(TEXT("DISPLAY"),NULL,NULL,NULL); rect.left=30; rect.right=100; rect.top=50; rect.bottom=200; FillRect(hdc,&rect,(HBRUSH)(RGB(40,151,151))); The error is: ERROR: The variable 'rect' is being used without being initialize
我是在Visual C ++中使用图形的新手。 我只是想做一个填充颜色的矩形。 需要帮助来纠正这个... RECT rect; HDC hdc; hdc=CreateDC(TEXT("DISPLAY"),NULL,NULL,NULL); rect.left=30; rect.right=100; rect.top=50; rect.bottom=200; FillRect(hdc,&rect,(HBRUSH)(RGB(40,151,151))); 错误是： ERROR: The variable 'rect' is being used without being initialized. 这通常是一个警告，而不是一个错误。 在这
I'm trying to implement a function to calculate pi using the taylor series, here is my code to do that #include <iostream> #include <math.h> using namespace std; double pi(int n) { double sum = 1.0; int sign = -1; for (int i = 1; i < n; i++) { sum += sign / (2.0 * i + 1.0); sign = -sign; } return 4.0 * sum; } int main() { cout << "the value for pi is" <&l
我试图实现一个函数来计算pi使用泰勒系列，这里是我的代码来做到这一点 #include <iostream> #include <math.h> using namespace std; double pi(int n) { double sum = 1.0; int sign = -1; for (int i = 1; i < n; i++) { sum += sign / (2.0 * i + 1.0); sign = -sign; } return 4.0 * sum; } int main() { cout << "the value for pi is" << pi ; } 出于某种原因，我的代码不断返
This question already has an answer here: C++11 Fun with initializer lists, arrays, and enumerations 5 answers That is uniform initialization, a new C++11 feature. However, it is arguably being used the right way in your example. It should be: Queue(const size_t &cap=8) : head(0),tail(0),count(0),data(cap) {} // ^^^^^ Because the
这个问题在这里已经有了答案： C ++ 11有趣的初始化列表，数组和枚举5个答案 这是统一的初始化，一个新的C ++ 11功能。 然而，在你的例子中，它可以被正确地使用。 它应该是： Queue(const size_t &cap=8) : head(0),tail(0),count(0),data(cap) {} // ^^^^^ 因为其目的是调用std::vector<>的构造函数，它接受std::vector<>的初始大小。 以这
I know there is bulk loading in b+tree. I just wanted to know is there any algorithm for bulk loading in B-Tree. For example given an array of data what is the best way to create a B-Tree? Actually The answer is yes. The main difference between B+-trees and plain B-trees is that the values are actually stored in the leaves for the former, while in the later you will find values in every nod
我知道在b +树中有批量加载。 我只是想知道在B-Tree中是否有批量加载的算法。 例如，给定一组数据，创建B树的最佳方式是什么？ 其实答案是肯定的。 B +树和纯B树的主要区别在于，值实际上存储在前者的叶子中，而后者则会在每个节点中找到值。 因此，B +树允许您以几乎连续的方式存储数据，每个叶包含整个排序数据的连续片段。 对于B树，这不是真的：一个内部节点将包含多个元素，但它们不会是连续的。 整个排序的数据集
I'm trying to implement various sorting algorithms and Radix Sorting (by Most Significant Digit) is giving me a pain: template <typename ITER> void RadixSortGroup_MSD(ITER start, ITER end, int radix) { std::array<std::vector<typename ITER::value_type>, 10> bins; // split into bins for(ITER idx = start; idx < end; ++idx) { bins[(*(idx) / radix) % 10].p
我试图实现各种排序算法和基数排序（由最重要的数字）给我一个痛苦： template <typename ITER> void RadixSortGroup_MSD(ITER start, ITER end, int radix) { std::array<std::vector<typename ITER::value_type>, 10> bins; // split into bins for(ITER idx = start; idx < end; ++idx) { bins[(*(idx) / radix) % 10].push_back(*idx); } // compile them together again
Is there a way (in Linux) to determine which libraries I must link a C/C++ program against? I do not want to miss a library, even in situations when undefined symbols would not be detected at program start. Also, I want to avoid unnecessary dependencies of course. I formulated this question generally, but here is a specific, nontrivial example: Until recently, I thought that I need to link ag
有没有办法（在Linux中）确定我必须链接C / C ++程序的库？ 即使在程序启动时未检测到未定义符号的情况下，我也不想错过图书馆。 另外，我想避免不必要的依赖关系。 我一般提出了这个问题，但这里是一个特殊的，不重要的例子：直到最近，我还以为我需要链接到使用Boost.Python开发的Python模块的libpython。 但是，这不是真的：用Boost.Python编写一个模块; 它甚至可能使用Python C API的函数，而不仅仅是Boost.Python。
I had an interview last week. I was stuck in one of the question in algorithm round. I answered that question, but the interviewer did not seem convinced. That's why I am sharing the same. Please tell me any optimized method for this question, so that it will help me in future interviews. Question :- There are 20 text files given, all files are ASCII text files, having size less than
上周我接受了采访。 我在算法轮回中遇到了一个问题。 我回答了这个问题，但面试官似乎并不相信。 这就是为什么我分享相同。 请告诉我有关此问题的任何优化方法，以便在未来的访谈中帮助我。 问题 ： - 共有20个文本文件，所有文件都是ASCII文本文件，大小小于10 ^ 9字节。 还有一个输入也给出了，这也是一个ASCII文件，比如input.txt。 我们的任务是将此输入文件的内容与给定的20个文件进行战略匹配，并打印最接近的
I am trying to extract images out of a mp4 video stream. After looking stuff up, it seems like the proper way of doing that is using Media Foundations in C++ and open the frame/read stuff out of it. There's very little by way of documentation and samples, but after some digging, it seems like some people have had success in doing this by reading frames into a texture and copying the conten
我正在尝试从mp4视频流中提取图像。 看完东西后，似乎正确的方法是在C ++中使用Media Foundations并从中打开框架/读取的东西。 通过文档和样本很少，但经过一些挖掘，似乎有些人通过将纹理读入框架并将该纹理的内容复制到内存可读纹理中来获得成功（我甚至没有当然如果我在这里使用正确的术语）。 尝试我发现虽然给了我错误，我可能做了一堆错误的东西。 下面是我尝试做的一小段代码（项目本身附在底部）。 ComPtr<
Rounding the result of division to the nearest integer is pretty simple. But I'm trying to round a result of division so that the subsequent operation will give the best approximation. That's best explained by a simple function: const int halfbits = std::numeric_limits<unsigned int>::digits / 2; unsigned x = foo(); // Likely big. unsigned x_div = x >> halfbits; // Rounded d
将除法结果舍入到最接近的整数非常简单。 但是我试图将分割的结果进行舍入，以便随后的操作能够给出最佳的近似值。 这最好通过一个简单的函数来解释： const int halfbits = std::numeric_limits<unsigned int>::digits / 2; unsigned x = foo(); // Likely big. unsigned x_div = x >> halfbits; // Rounded down unsigned y = x_div * x_div; // Will fit due to division. 我可以通过添加1<<(halfbits-