小编Omn*_*ous的帖子

编辑:我在这里重新问了同样的问题(解决了这个问题后面的问题):为什么这个C++ 0x程序会产生意外的输出？

基本的想法是,如果你不小心,指向可移动的东西可能会给你带来一些奇怪的结果.

C++移动构造函数和移动赋值运算符看起来非常积极.它们可以在复制构造函数没有意义的情况下使用,因为它们不需要重复指向的资源.

但有些情况下,如果你不小心,他们会咬你.这是特别相关的,因为我已经看到允许编译器生成移动构造函数的默认实现的建议.如果有人能给我一个,我会提供一个链接.

所以,这里有一些代码有一些可能不完全明显的缺陷.我测试了代码,以确保它使用-std=gnuc++0x标志以g ++编译.这些缺陷是什么？你会如何修复它们？

#if (__cplusplus <= 199711L) && !defined(__GXX_EXPERIMENTAL_CXX0X__)
   #error This requires c++0x
#endif

#include <unordered_set>
#include <vector>
#include <utility>
#include <algorithm>

class ObserverInterface {
 public:
   virtual ~ObserverInterface() {}

   virtual void observedChanged() = 0;
   virtual void observedGoingAway() = 0;
};

class Observed {
 private:
   typedef ::std::unordered_set<ObserverInterface *> obcontainer_t;

 public:
   Observed() {}
   Observed(const Observed &) = delete;
   const Observed &operator =(const Observed &b) = delete;
   // g++ does not currently support defaulting the …

我认为C++中有保留关键字,为什么它们被称为"保留关键字"并被归类为不同？

EI具有作为向量的参数指针的函数:

void Function(std::vector<type>* aa)

现在在这个函数里面我想过滤掉从那个向量到另一个向量的数据,我想通过改变这个临时值的值来改变原始向量的数据.该死的很难理解:

void Function(std::vector<type>* aa)
{
    std::vector<type*> temp; //to this vector I filter out data and by changning 
    //values of this vector I want to autmatically change values of aa vector
}

我有类似的东西:

void Announce_Event(std::vector<Event>& foo)
{
    std::vector<Event> current;
    tm current_time = {0,0,0,0,0,0,0,0,0};
    time_t thetime;
    thetime = time(NULL);
    localtime_s(&current_time, &thetime);
    for (unsigned i = 0; i < foo.size(); ++i) {
        if (foo[i].day == current_time.tm_mday &&
            foo[i].month == current_time.tm_mon &&
            foo[i].year == current_time.tm_year+1900)
        {
            current.push_back(foo[i]);
        }
    }
    std::cout …

所以我正在编写这个程序来执行一个基本任务菜单,其中一个是告诉用户输入的字符是大写,小写还是不是字母.

#include <iostream>
using namespace std;

int main () {

    int mi;

    cout << "1) Area of Circle" << endl;
    cout << "2) Character Detection" << endl;
    cout << "3) Capitalization 1-3-5" << endl;
    cout << "4) Binomial Roots" << endl;
    cout << "0) Quit" << endl;

    cin >> mi;

    switch (mi) {
        case 2:
        {
            char c;
            cout << "input a character:  ";
            cin.get(c);
            cin.ignore(); /////// unsure if using this properly
            if ('a' <= c && c <= 'z') …

project1.cpp

#include "stdafx.h"
#include "Bicycle.cpp"
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    bool runP = true;
    do {
    Bicycle object();
    char oType;
    cout << "Would you like a (B)icycle, or (A)nimal? E for Exit\n";
    cin >> oType;

    if (oType == 'B' || oType == 'b') {
        int seat, wheels;
        string brand;
        cout << "How many wheels does the bike have?\n";
        cin >> wheels;
        object().setWheels(wheels);
        cout << "How many seats does the bike have?\n";
        cin >> seat;
        object().setSeats(seat);
        cout …

当我看到虚拟虚空enter（）= 0时，我正在读书。赋值不是变量时该怎么办？

class MapSite { 
public: 
virtual void Enter() = 0; 
};