containers

问题 C++11 provides multiple ways to iterate over containers. For example: Range-based loop for(auto c : container) fun(c) std::for_each for_each(container.begin(),container.end(),fun) However what is the recommended way to iterate over two (or more) containers of the same size to accomplish something like: for(unsigned i = 0; i < containerA.size(); ++i) { containerA[i] = containerB[i]; } 回答1: Rather late to the party. But: I would iterate over indices. But not with the classical for loop but

问题 I\'m wondering why I can\'t use STL maps with user-defined classes. When I compile the code below, I get the following cryptic error message. What does it mean? Also, why is it only happening with user-defined types? (Primitive types are okay when they are used as key.) C:\\MinGW\\bin..\\lib\\gcc\\mingw32\\3.4.5........\\include\\c++\\3.4.5\\bits\\stl_function.h||In member function `bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = Class1]\':| C:\\MinGW\\bin..\\lib\

问题 I saw this nice graphic which classifies which STL container would suit based on different requirements of data such as: -- Fixed Size Vs Variable size -- Data of same tyme Vs different type -- Sorted Vs unsorted data -- Sequential Vs random access http://plasmahh.projectiwear.org/cce_clean.svg I notice in that image, that C++ STL there is no container which is Variable Size Heterogenous (data of different types). Doesn\'t C++ have something for this? PS - There can be many permutations made

问题 As we all know we have beans as singleton by default in Spring container and if we have a web application based on Spring framework then in that case do we really need to implement Singleton design pattern to hold global data rather than just creating a bean through spring. Please bear with me if I\'m not able to explain what I actually meant to ask. 回答1: A singleton bean in Spring and the singleton pattern are quite different. Singleton pattern says that one and only one instance of a

问题 Item 18 of Scott Meyers\'s book Effective STL: 50 Specific Ways to Improve Your Use of the Standard Template Library says to avoid vector <bool> as it\'s not an STL container and it doesn\'t really hold bool s. The following code: vector <bool> v; bool *pb =&v[0]; will not compile, violating a requirement of STL containers. Error: cannot convert \'std::vector<bool>::reference* {aka std::_Bit_reference*}\' to \'bool*\' in initialization vector<T>::operator [] return type is supposed to be T& ,

问题 Apparently ;-) the standard containers provide some form of guarantees. What type of guarantees and what exactly are the differences between the different types of container? Working from the SGI page (about STL) I have come up with this: Container Types: ================ Container: Forward Container Reverse Container Random Access Container Sequence Front Insert Sequence Back Insert Sequence Associative Container Simple Associative Container Pair Associative Container Sorted Associative

问题 I am trying to run a cronjob inside a docker container that invokes a shell script. Yesterday I have been searching all over the web and stack overflow, but I could not really find a solution that works. How can I do this? EDIT: I\'ve created a (commented) github repository with a working docker cron container that invokes a shell script at given interval. 回答1: You can copy your crontab into an image, in order for the container launched from said image to run the job. See "Run a cron job with

问题 I keep rereading the Docker documentation to try to understand the difference between Docker and a full VM. How does it manage to provide a full filesystem, isolated networking environment, etc. without being as heavy? Why is deploying software to a Docker image (if that\'s the right term) easier than simply deploying to a consistent production environment? 回答1: Docker originally used LinuX Containers (LXC), but later switched to runC (formerly known as libcontainer ), which runs in the same