What is the easiest way of getting a char array from a vector? The way I am doing is getting a string initialized using vector begin and end iterators, and then getting .c_str() from this string. Are there other efficient methods? This was discussed in Scott Meyers' Effective STL, that you can do &vec[0] to get the address of the first element of an std::vector , and since the standa
从矢量中获取char数组的最简单方法是什么？ 我在做的方式是使用向量开始和结束迭代器初始化字符串，然后从此字符串获取.c_str（）。 还有其他有效的方法吗？ 这在Scott Meyers的Effective STL中已经讨论过了，你可以通过&vec[0]获得std::vector的第一个元素的地址，并且由于标准限制了vector的连续内存，所以你可以做这样的事情。 // some function void doSomething(char *cptr, int n) { } // in your code std::ve
I'm wrapping up user space linux socket functionality in some C++ for an embedded system (yes, this is probably reinventing the wheel again). I want to offer a read and write implementation using a vector. Doing the write is pretty easy, I can just pass &myvec[0] and avoid unnecessary copying. I'd like to do the same and read directly into a vector, rather than reading into a cha
我在一些嵌入式系统的C ++中封装了用户空间linux套接字功能（是的，这可能是再次重新发明轮子）。 我想提供一个使用矢量的读写实现。 做写操作非常简单，我只需传递&myvec[0]并避免不必要的复制。 我想要做同样的事情，并直接读入一个向量，而不是读入char缓冲区，然后将所有这些拷贝到一个新创建的向量中。 现在，我知道要读取多少数据，并且可以正确分配（ vec.reserve() ）。 我也可以读入&myvec[0] ，尽管这
I'm debugging C++ program compiled with MSVC under Windows. I want to investigate issue linked with multi threading. So I put ASSERT in my code and when program reaches ASSERT it displays window about ASSERT (Standart [Abort], [Retry], [Ignore] window) with proposal to pause program in debugger. I press [Retry] button and program pauses. BUT while I was pressing the button other threads c
我在Windows下调试用MSVC编译的C ++程序。 我想调查与多线程相关的问题。 所以我把ASSERT放入我的代码中，当程序到达ASSERT时，它会显示关于ASSERT（Standart [Abort]，[Retry]，[Ignore]窗口）的窗口，并建议在调试器中暂停程序。 我按下[重试]按钮并暂停程序。 但是当我按下按钮时，其他线程继续执行。 所以问题是如何在程序到达某个点时立即停止该程序，以查看当时其他线程在做什么？ 您可能需要设置条件断点而不是使
C++ enum question. So I have a list of files, and their IDs that I need to iterate over, and do stuff to. Most of the stuff is the same, but there are a few file-specific things that need to be done. I tried putting the file IDs in an enum, and iterating over that. Howver, the fileIDs are non contiguous, and jump around. Currently, I have something akin to this for(int i = 0; i < FILE_
C ++枚举问题。 因此，我有一个文件列表，以及我需要重复执行的文件列表，并执行一些操作。 大部分的东西都是一样的，但有一些文件特定的事情需要完成。 我试着把文件ID放在一个枚举中，并迭代它。 不管怎样，fileIDs是不连续的，并跳过。 目前，我有类似的东西 for(int i = 0; i < FILE_ENUM_MAX; i++) { currentFile = myEnum(i); // do stuff } enum myEnum { file1 = 0x1111, file2 = 0x8000,
I need to place uuids at locations in memory that I don't control (a pointer is passed to me (to shm backed by file)), but I have to make sure that what I store at the given pointers will be portable, ie I would like to use boost::endian to settle on little endian for the uuids. Is it possible to combine boost::endian and boost:uuid for that? You don't need to worry about endianness wi
我需要将uuids放置在我不控制的内存中（一个指针传递给我（shm支持文件）），但是我必须确保存储在给定指针处的内容是可移植的，即我想使用boost :: endian来解决uuids的小端问题。 是否有可能结合boost :: endian和boost：uuid？ 您无需担心UUID的排序问题。 他们不被视为数值。 它们只是16个字节的不透明块。 您可以在UUID上执行的唯一有意义的操作是比较相等性。 UUID的字节顺序很重要（与@Ferruccio相反）。 UUID的
I want to understand why the following code behaves differently on my linux and windows 7 machines: On linux it takes ~120ms per iteration. On windows 7 already the first iteration takes 0.4 seconds and subsequent iterations take much longer. Iteration 8 already takes about 11 seconds, iteration 22 takes roughly 1 minute. I observed this behaviour on different hardware. It seems to be relate
我想了解为什么下面的代码在我的linux和windows 7机器上表现不同：在linux上，每次迭代需要大约120ms。 在Windows 7上，第一次迭代需要0.4秒，随后的迭代需要更长的时间。 迭代8已经大约需要11秒，迭代22需要大约1分钟。 我在不同的硬件上观察了这种行为。 这似乎与Windows有关。 #include <iostream> #include <time.h> #include <chrono> void iteration() { int n = 25000; // Allocate memory
Let's check if struct Thing { int foo(double, bool) {return 0;} }; has the int foo(double, bool) member function during compile time. There are many ways of doing this, and most are just variations of others. Can someone think of a way that is vastly different (or at least fairly creative) than the 5 ways I mention here? I'm just trying to learn some new techniques with templates
我们来检查一下 struct Thing { int foo(double, bool) {return 0;} }; 在编译期间具有int foo(double, bool)成员函数。 有很多方法可以做到这一点，大多数只是其他的变种。 有人能想出一种与我在这里提到的5种方式截然不同（或者至少相当有创意）的方式吗？ 我只是想通过模板和SFINAE学习一些新技术。 #include <iostream> #include <type_traits> // Using void_t (this includes using std::is_detecte
I'm currently in a situation where I would like to duplicate some elements in a vector. In short, my code is similar to the following: std::vector<MyStruct> v; // ... auto toDuplicate = std::find(v.begin(), v.end(), [](const MyStruct &s) { return true; /*In reality, a bit more complex*/ }); v.insert(toDuplicate, nrOfDuplicates-1, *toDuplicate); // Signature: insert(iterator, size_
我目前处于想要在矢量中复制某些元素的情况。 总之，我的代码类似于以下内容： std::vector<MyStruct> v; // ... auto toDuplicate = std::find(v.begin(), v.end(), [](const MyStruct &s) { return true; /*In reality, a bit more complex*/ }); v.insert(toDuplicate, nrOfDuplicates-1, *toDuplicate); // Signature: insert(iterator, size_t, const value_type &) 因此，在这种情况下，如果容量小于最终
As a pre-req: I am fairly new to C++ / C I work with a server side C++ application that recently had a major memory leak. I was able to diagnose and subsequently fix the memory leak with the help of UMDH. The leak was in one of the primary DLLs that is written in C. After correcting this, I started to review other potential leaks that UMDH had reported. The next biggest reported leak appeare
作为pre-req：我对C ++ / C相当陌生 我使用最近发生内存泄漏的服务器端C ++应用程序。 在UMDH的帮助下，我能够诊断并修复内存泄漏。 泄漏发生在用C编写的主DLL之一。在纠正这个问题后，我开始回顾UMDH报道的其他潜在泄漏。 下一个最大的报告泄漏似乎来自Maria DB连接器库 - >与SQL DB交互，我们使用LoadLibraryA加载Maria DB连接器库。 一旦我们进入DLL，这就是调用堆栈中的一个： libmariadb!_heap_alloc_base+0000005
I have an issue while unloading a dll. It is like this one but quit different. I'm loading a dll using LoadLibraryA then call a function and close the dll with FreeLibrary. However, the dll is not unloaded but FreeLibrary return success. reduced code: void foo() { std::unique_lock<std::mutex> lock(mtx_); } While debugging the code and looking into Process Explorer unique_lock
卸载dll时遇到问题。 它就像这个一样，但不一样。 我正在使用LoadLibraryA加载DLL，然后调用函数并使用FreeLibrary关闭DLL。 但是，该DLL不卸载，但FreeLibrary返回成功。 简化代码： void foo() { std::unique_lock<std::mutex> lock(mtx_); } 在调试代码并查看Process Explorer时，unique_lock会创建第二个线程， 但为什么 ？ 此线程只要应用程序运行就运行。 除此之外没有别的; 没有其他句柄的DLL，没有其