stl

问题 I'm new to using c++ and I don't really know how to use the STL lists. I'm making a graph of intersections of city streets. Here's my structs/header files: global header #ifndef GLOBAL_H #define GLOBAL_H typedef struct Vertex_ vertex; typedef struct Edge_ ege; #endif vertex header #ifndef VERTEX_H #define VERTEX_H #include<list> #include "global.h" #include "edgelist.h" struct Vertex_{ int xsect; int danger; char xstreet[25]; list<Edge_> EdgeList; struct Vertex_ *next; struct Vertex_ *prev; }

问题 Every Variable in c++ has some type like in int i , i has a type int . Similarly we have iterators in STL which we declare say something like this map<string,int>::iterator it . What is the type of the it over here ? Is it pointer type or is it a pointer type as we gerally deference iterators to fetch values associated or pointed by those itearors in case of vectors which store int or some other type.? Or the operator * is overloaded for iterators in STL ? 回答1: 24.2.1/1 [iterator.requirements

问题 This question already has answers here : const reference data member bound to a temporary initializing that reference in a constructor (2 answers) Closed 3 years ago . I am trying to use the Presage text-prediction platform in a Qt5 project but keep getting errors due to std::strings being corrupted. I have this class providing string contexts for the predictive system: class SomeClass : public ParentClass { public: SomeClass(const std::string& _past_context) : past_context(_past_context) { }

问题 Normally compare function of sort in c++ takes two arguments e.g: sort(v.begin(),v.end(),compare); bool compare(int a,int b) . . . But in the vector I have stored an array and I want to sort the vector based on a particular index. viz: int arr[3]; vector<arr> v; How can I use sort function if I want to sort v based on index 0 or 1 or 2(depending on user's input)? Here problem is that when I will write compare function: bool compare(int *arr,int *arr1) then how can I tell this function to sort

问题 Normally compare function of sort in c++ takes two arguments e.g: sort(v.begin(),v.end(),compare); bool compare(int a,int b) . . . But in the vector I have stored an array and I want to sort the vector based on a particular index. viz: int arr[3]; vector<arr> v; How can I use sort function if I want to sort v based on index 0 or 1 or 2(depending on user's input)? Here problem is that when I will write compare function: bool compare(int *arr,int *arr1) then how can I tell this function to sort

问题 I'm aware that mixing debug and release libraries that pass STL containers to each other causes big problems. But what exactly in 'debug' or 'release' causes this? I have a QT project that gets built as 'release', but it has /DEBUG added to the compiler flags. If I build another QT project under 'debug' (which also has the /DEBUG flag), are they compatible? Or is there an optimization flag or some other flag that makes them incompatible? Basically, is there a way I can look at the compilation

问题 It is follow-up question for this MIC question. When adding items to the vector of reference wrappers I spend about 80% of time inside ++ operator whatever iterating approach I choose. The query works as following VersionView getVersionData(int subdeliveryGroupId, int retargetingId, const std::wstring &flightName) const { VersionView versions; for (auto i = 0; i < 3; ++i) { for (auto j = 0; j < 3; ++j) { versions.insert(m_data.get<mvKey>().equal_range(boost::make_tuple(subdeliveryGroupId + i,

问题 I have a class: class Monster : public Player { public: // Copy constructor - used for populating monster list in Game class Monster(int newType) { type = newType; canmove = true; notforward = false; } int type; bool operator==(const Monster& m) const {return type == m.type;} bool operator!=(const Monster& m) const {return type != m.type;} bool operator< (const Monster& m) const {return type < m.type;} bool operator<=(const Monster& m) const {return type <= m.type;} bool operator> (const

问题 I am trying to sort a buffer using STL sort. Now, Im using qsort but i read that stlsort has a better performance because of the inline "compare" function. The buffer has elements of size 52. It has, for example, 1024 elements of size 52. Here is a part of my code. It is working well, but I want to use the STL sort. I am sorting a fixed length file. Each fixed length file has a record size, so the user has to inform the record size. In the example below i put 52. HANDLE hInFile; char *

问题 I'm building C++ code in Eclipse CDT with g++ and I'm getting the following linker error: Undefined symbols for architecture x86_64: "std::__throw_bad_function_call()", referenced from: std::function<void (graphics::RenderingContext*)>::operator()(graphics::RenderingContext*) const in GameWindow.o I have std::function members in a class called GameWindow. Is there something I have to link to in order to get code using std::function to link properly? 回答1: Turns out my lib path wasn't set