In R, I am using an internal C++ structure to store the data (Using R_ExternalPtr). The data can then be processed using various functions. Here is a simple example (the real data structure is much more complex): #include <Rinternals.h> class MyObject{ public: int type; MyObject(int t):type(t){} }; void finalizeMyObject(SEXP ptr){ MyObject * mo= static_cast&
在R中，我使用内部C ++结构来存储数据（使用R_ExternalPtr）。 然后可以使用各种功能处理数据。 这是一个简单的例子（真正的数据结构更复杂）： #include <Rinternals.h> class MyObject{ public: int type; MyObject(int t):type(t){} }; void finalizeMyObject(SEXP ptr){ MyObject * mo= static_cast<MyObject *>(R_ExternalPtrAddr(ptr)); delete mo; } extern "C" {
When debugging a segfault error in a cross compiled embedded linux environment, I isolated the problem to be a call of memset. Further investigation showed, that there is something strange going on. I tried to run a test application on the target with the following code: string st; st = "teststring"; std::cout << "address: " << &st << std::endl; std::cout << "sizeo
在交叉编译的嵌入式Linux环境中调试segfault错误时，我将问题隔离为memset的调用。 进一步的调查显示，有一些奇怪的事情发生。 我试图用以下代码在目标上运行测试应用程序： string st; st = "teststring"; std::cout << "address: " << &st << std::endl; std::cout << "sizeof: " << sizeof(st) << std::endl; std::cout << "value (before): " << st << std::e
TL/DR : Where can I find more information about building a GCC 4.7.0 cross-compiling toolchain for ARM (gnueabi) platform (intended to run on a Raspberry Pi device)? I have just got a brand new Raspberry Pi and I am very eager to start programming for it. I've managed to install the GCC toolchain (I am using the Arch Linux system image) and compiled some basic programs, all working fine.
TL / DR ：我在哪里可以找到关于为ARM（gnueabi）平台（旨在运行在Raspberry Pi设备上）构建GCC 4.7.0交叉编译工具链的更多信息？ 我刚刚买了一个全新的树莓派，我非常渴望为它开始编程。 我设法安装了GCC工具链（我正在使用Arch Linux系统映像）并编译了一些基本程序，所有工作都很好。 我也尝试编译Boost库，因为我经常在我的项目中使用它们，并且除了编译速度很慢之外，所有内容似乎都可以正常工作（ ./bootstrap.sh + .
I'm looking at the disassembly for a critical function in our code. It takes about 90% of the performance'. Not entirely surprising, as it's a very big function after inlining and so it ends up doing a lot. However, I noticed that there is some assembly I don't understand the justification for: test rsi, rsi je setecx0 cmp rsi, 0x1 je setecx1 cmp rsi, 0x2 je setecx2 cmp rsi,
我正在研究代码中的关键功能的反汇编。 它大约需要90％的表现。 这并不令人惊讶，因为内联后它是一个非常大的功能，所以它最终会做很多事情。 但是，我注意到有一些程序集我不明白这样做的理由： test rsi, rsi je setecx0 cmp rsi, 0x1 je setecx1 cmp rsi, 0x2 je setecx2 cmp rsi, 0x3 je setecx3 cmp rsi, 0x4 je setecx4 mov ecx, 0x5 ; Code that doesn't use ECX yet ecxnotzero: cmp r9, rsi je epilog ecxzero: ; L
Greetings all, in my application i use the following code: bool HandleMessages() { MSG msg; if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) { if (msg.message == WM_QUIT) return FALSE; TranslateMessage(&msg); DispatchMessage(&msg); } return true; } This is the standard code for message handling in windows i thought, but now when i try to run the program, i alwa
问候所有， 在我的应用程序中，我使用下面的代码： bool HandleMessages() { MSG msg; if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) { if (msg.message == WM_QUIT) return FALSE; TranslateMessage(&msg); DispatchMessage(&msg); } return true; } 这是我认为在windows中处理消息的标准代码，但现在当我尝试运行该程序时，我总是在PeekMessage（）调用中获得一个Exception。 异常
I reproduce the problem by this simple demo: // bool_test_func.cpp #include <stdio.h> void func(bool* b) { int a = (*b ? 0 : 1); printf("%dn", a); // EXPECT ether 0 or 1 here } // bool_test.cpp void func(bool* b); int main() { int n = 128; func((bool*)&n); return 0; } -O0 compile and run: g++ -g -O0 -Wall -o bool_test bool_test.cpp bool_test_func.cpp mikewei@maclinux:~/t
我通过这个简单的演示重现了这个问题： // bool_test_func.cpp #include <stdio.h> void func(bool* b) { int a = (*b ? 0 : 1); printf("%dn", a); // EXPECT ether 0 or 1 here } // bool_test.cpp void func(bool* b); int main() { int n = 128; func((bool*)&n); return 0; } -O0编译并运行： g++ -g -O0 -Wall -o bool_test bool_test.cpp bool_test_func.cpp mikewei@maclinux:~/testing/c++$ .
It seems pretty clear that it is supposed to set things up. When exactly does it run? Why are there two parentheses? Is __attribute__ a function? A macro? Syntax? Does this work in C? C++? Does the function it works with need to be static? When does __attribute__((destructor)) run? Example in Objective C: __attribute__((constructor)) static void initialize_navigationBarImages()
这似乎很清楚，它应该设置的东西。 它何时运行？ 为什么有两个括号？ __attribute__是一个函数吗？ 宏？ 句法？ 这在C中工作吗？ C ++？ 它与它一起工作的功能需要是静态的吗？ 什么时候__attribute__((destructor))运行？ 目标C中的示例： __attribute__((constructor)) static void initialize_navigationBarImages() { navigationBarImages = [[NSMutableDictionary alloc] init]; } __attribute__((dest
Note: I'd appreciate more of a guide to how to approach and come up with these kinds of solutions rather than the solution itself. I have a very performance-critical function in my system showing up as a number one profiling hotspot in specific contexts. It's in the middle of a k-means iteration (already multi-threaded using a parallel for processing sub-ranges of points in each worker
注意：我希望更多地了解如何处理和提出这些解决方案，而不是解决方案本身。 在我的系统中，我有一个非常关键的性能功能，在特定环境下显示为头号性能分析热点。 它处于k-means迭代的中间（已经使用并行处理多线程来处理每个工作线程中的点的子范围）。 ClusterPoint& pt = points[j]; pt.min_index = -1; pt.min_dist = numeric_limits<float>::max(); for (int i=0; i < num_centroids; ++i) { const Clust
Possible Duplicate: In C arrays why is this true? a[5] == 5[a] A friend of mine is learning C++ for the first time, and sent me this snippet: int foo[] = { 3, 38, 38, 0, 19, 21, 3, 11, 19, 42 }; char bar[] = " abcdefghijklmnopqrstuvwxyz01234567890+-,.!?-_"; for (int i = 0; i < 10; ++i) { std::cout << foo[i][bar]; } At a glance, I told him it won't work - I thought it wouldn&
可能重复： 在C数组中，为什么这是真的？ a [5] == 5 [a] 我的一个朋友第一次学习C ++，并且给我发了这个片段： int foo[] = { 3, 38, 38, 0, 19, 21, 3, 11, 19, 42 }; char bar[] = " abcdefghijklmnopqrstuvwxyz01234567890+-,.!?-_"; for (int i = 0; i < 10; ++i) { std::cout << foo[i][bar]; } 乍一看，我告诉他它不会工作 - 我认为它不会编译，或者至少会导致访问冲突，因为foo不是一个二维数组，他回
After a most recent software update on my mac, I'm not able to compile and link a c++ hello world program without sudo. The program (helloworld.cpp): #include <iostream> int main(){ std::cout << "hello worldn"; return 0; } The invocation: clang++ helloworld.cpp Fails with error: ld: can't write output file: a.out for architecture x86_64 clang: error: linker comman
在我的Mac上进行了最新的软件更新之后，我无法编译和链接没有sudo的c ++ hello world程序。 该程序（helloworld.cpp）： #include <iostream> int main(){ std::cout << "hello worldn"; return 0; } 调用： clang++ helloworld.cpp 失败，错误： ld：无法写入输出文件：体系结构x86_64的a.out clang：error：linker命令失败，退出代码1（使用-v查看调用） 但如果我在sudo下执行此操作， sudo clang+