How do I get type conversion to work when cascading the type conversions? The following code should be simple, but converison from TypeB to int requires the compiler to deduce two type conversions automatically. But it does not. I can not simply implement operator int() const { return val; } on the TypeB class because this is supposed to be a template class And I can not know which type to
级联类型转换时，如何让类型转换工作？ 下面的代码应该很简单，但是从TypeB到int的转换需要编译器自动推导出两种类型的转换。 但事实并非如此。 我不能简单地实现运算符int（）const {return val; } TypeB类，因为这应该是一个模板类我不知道要转换为哪种类型。 class TypeA { public: TypeA( int a ) : val( a ) {} operator int () const { return val; } private: int val; }; class TypeB { public: Type
I incurred in a compiler dependent issue with the following code (stored in crtp.cc): #include <vector> #include <cassert> #include <iostream> template < class Derived > class AlgebraicVectorExpression { public: typedef std::vector<double>::size_type SizeType; typedef std::vector<double>::value_type ValueType; typedef std::vector<double>::referen
使用下面的代码（存储在crtp.cc中）引发了依赖于编译器的问题： #include <vector> #include <cassert> #include <iostream> template < class Derived > class AlgebraicVectorExpression { public: typedef std::vector<double>::size_type SizeType; typedef std::vector<double>::value_type ValueType; typedef std::vector<double>::reference ReferenceType; Size
I'm trying to use the visitor pattern to perform operations for the AST of my compiler but I can't seem to figure out an implementation that will work properly. AST classes excerpt: class AstNode { public: AstNode() {} }; class Program : public AstNode { public: std::vector<std::shared_ptr<Class>> classes; Program(const std::vector<std::shared_ptr<Class&
我试图使用访问者模式来执行我的编译器的AST操作，但我似乎无法弄清楚可以正常工作的实现。 AST课堂摘录： class AstNode { public: AstNode() {} }; class Program : public AstNode { public: std::vector<std::shared_ptr<Class>> classes; Program(const std::vector<std::shared_ptr<Class>>&); void accept(AstNodeVisitor& visitor) const { visitor.visit(*this);
I have a string like "0189", for which I need to generate all subsequences, but the ordering of the individual characters must be kept, ie, here 9 should not come before 0, 1 or 8. Ex: 0, 018, 01, 09, 0189, 18, 19, 019, etc. Another example is "10292" for which subsequences would be: 1, 10, 02, 02, 09, 29, 92, etc. As you might have noticed '02' two times, since '
我有一个类似“0189”的字符串，为此我需要生成所有的子序列，但是必须保留单个字符的顺序，即这里9不应该在0,1或8之前出现。例如：0,018,01 ，09,0189,18,19,019等。 另一个例子是“10292”，其中的子序列是：1,10,02,02,09,29,92等。由于'2'在给定字符串中出现了两次，因此您可能已经注意到'02'两次了。 但是，像21：01,91那样的事情是无效的，因为要维持秩序。 任何算法或伪代码，可以在C / C ++中实现，将
[SOLVED] I'm having trouble getting this simple makefile to work properly. This should build the three source files NeonAs1.cpp NeonAs2.cpp NeonAs3.cpp to object files in the 'obj' folder. This works but it only ever attempts to build NeonAs1.cpp and then completes without error. Any ideas? WORKSPACE=../../workspace/ SRC_FOLDER=$(WORKSPACE)/ProjectNeon/ LOCAL_SRC_FILES=NeonAs
[解决了] 我无法让这个简单的makefile正常工作。 这应该建立三个源文件NeonAs1.cpp NeonAs2.cpp NeonAs3.cpp到'obj'文件夹中的目标文件。 这工作，但它只试图建立NeonAs1.cpp，然后完成没有错误。 有任何想法吗？ WORKSPACE=../../workspace/ SRC_FOLDER=$(WORKSPACE)/ProjectNeon/ LOCAL_SRC_FILES=NeonAs1.cpp NeonAs2.cpp NeonAs3.cpp vpath %.cpp $(SRC_FOLDER) OBJECTS = $(patsubst %.cpp,obj/%.o,$(LOC
In order to make the directory strcuture of my project a bit more organized I want to put sourcefiles for the same modules into seperate directory. All objectfiles should be put into obj directory. I don't really want to replicate the source tree in the obj directory as well, so I'm looking for a way to remove the directory part from a source file to make it into the obj path. So this
为了让我的项目的目录strcuture更加有组织，我想把相同模块的源文件放到单独的目录中。 所有的对象文件都应该放入obj目录。 我真的不想复制obj目录中的源代码树，所以我正在寻找一种方法从源文件中删除目录部分，使其进入obj路径。 所以这是当前版本，它要求obj目录与源目录具有相同的布局。 OBJDIR:= obj SRCDIR:= src SRC := propertyfile/propertyfile.cpp otheritems/file.cpp otheritmes/subtree/bla.cpp OBJ := $(pat
We are required to use a Makefile to pull everything together for our project but our professor never showed us how to. I only have ONE file, a3driver.cpp . The driver imports a class from a location "/user/cse232/Examples/example32.sequence.cpp" . That's it, everything else is contained with the .cpp . How would I go about making a simple Makefile that creates an executable
我们被要求使用一个Makefile来为我们的项目整合所有东西，但是我们的教授从来没有告诉我们如何去做。 我只有一个文件， a3driver.cpp 。 驱动程序从位置"/user/cse232/Examples/example32.sequence.cpp"导入一个类。 就是这样，其他所有内容都包含在.cpp 。 我将如何去做一个简单的Makefile来创建一个名为a3a.exe的可执行文件？ 从我为物理学毕业生写的维基文章中复制。 由于这是用于unix的可执行文件没有
Can epoll (on Linux) be somehow useful for regular files? I know it's primarily used with sockets but just wonder. Not really. epoll only makes sense for file descriptors which would normally exhibit blocking behavior on read/write, like pipes and sockets. Normal file descriptors will always either return a result or end-of-file more or less immediately, so epoll wouldn't do anything
epoll （在Linux上）对普通文件有用吗？ 我知道它主要用于套接字，但只是想知道。 不是真的。 epoll只对文件描述符有意义，通常在读/写时会出现阻塞行为，如管道和套接字。 普通的文件描述符会一直或多或少地立即返回一个结果或文件结束，所以epoll不会对它们做任何有用的事情。 我认为，EPERM会在epoll_ctl上失败： EPERM The target file fd does not support epoll. 如果该文件没有poll()接口。 实际的代码是h
I am trying to get the correct error code out of errno when opening a directory as a file, both with fopen as well as with ifstream.open(). I expect EISDIR, I get EACCES. I am compiling (and executing) with the MSVC 12.0 toolchain on Windows 7 x64. I have been reading in article (https://gehrcke.de/2011/06/reading-files-in-c-using-ifstream-dealing-correctly-with-badbit-failbit-eofbit-and-per
我试图用fopen以及ifstream.open（）打开一个目录作为文件时，从errno中获取正确的错误代码。 我期待EISDIR，我会得到EACCES。 我正在编译（并执行）Windows 7 x64上的MSVC 12.0工具链。 我一直在阅读文章（https://gehrcke.de/2011/06/reading-files-in-c-using-ifstream-dealing-correctly-with-badbit-failbit-eofbit-and-perror/），其中作者得到了输出“流失败位（或badbit）。错误状态：是一个目录”。 我使用GCC 4.6
I don't understand what is throwing the exception here with my input file stream. I have done almost the exact thing before without any problems. std::string accnts_input_file = "absolute_path/account_storage.txt"; std::string strLine; std::ifstream istream; istream.exceptions( std::ifstream::failbit | std::ifstream::badbit ); try { istream.open( accnts_input_file.c_str() ); while
我不明白什么是在我的输入文件流中抛出异常。 我已经完成了几乎确切的事情，没有任何问题。 std::string accnts_input_file = "absolute_path/account_storage.txt"; std::string strLine; std::ifstream istream; istream.exceptions( std::ifstream::failbit | std::ifstream::badbit ); try { istream.open( accnts_input_file.c_str() ); while( std::getline( istream, strLine ) ) { std::cout <