c++ 上的向量迭代器

Question

我有以下內容：

#ifndef APPSYSTEM_H
#define APPSYSTEM_H
#include "Application.h"
#include <iostream>
#include <exception>
#include <vector>
#include <iterator>

using namespace std;

class AppSystem{
   private:
       vector<Application> &ApplicationVector;
   public:
    AppSystem(); //AppSystem Constructor
    AppSystem(const AppSystem &); //Copy constructor
    void setApplicationVector(vector<Application> &); //Set the AppSystem's Application Vector
    vector<Application> getApplicationVector(); //Get the AppSystem's Application Vector
    void PushAppToApplicationVector(Application &) const; //Push Data to ApplicationVector
    Application &PopAppFromApplicationVector(Application &) const; //Pop Data from ApplicationVector
    vector<Application>::iterator FindAppToApplicationVector(Application &) const; //Find if Data belongs to ApplicationVector
    void DeleteAppFromApplicationVector(Application &); //Delete Data from ApplicationVector
    void ClearAllpicationVector(); //Clear all data from ApplicationVector
    virtual ~AppSystem(); //Destructor
};

#endif /* APPSYSTEM_H */

// APPSYSTEM.cpp file

//Find if Data belongs to ApplicationVector
vector<Application>::iterator AppSystem::FindAppToApplicationVector(Application &app) const{
   vector<Application>::iterator it;
   for (it = this->ApplicationVector.begin(); it = this->ApplicationVector.end(); it++){
       if (*it == app){
          return it; 
       }
}

我收到此錯誤：

AppSystem.cpp:56:51: error: could not convert '(it = (&((const AppSystem*)this)->AppSystem::ApplicationVector)->std::vector<_Tp, _Alloc>::end<Application, std::allocator<Application> >())' from 'std::vector<Application>::iterator {aka __gnu_cxx::__normal_iterator<Application*, std::vector<Application> >}' to 'bool'
 for (it = this->ApplicationVector.begin(); it = this->ApplicationVector.end(); it++)

有什么建議么？

Answer 1

在這條線上

for (it = this->ApplicationVector.begin(); it = this->ApplicationVector.end(); it++)

您正在使用分配等於不測試相等性。 用it.= this->ApplicationVector.end()

Answer 2

在 for 循環的條件下，您正在分配it ，而不是與end()的結果進行比較。 你需要做：

for (it = this->ApplicationVector.begin(); 
     it != this->ApplicationVector.end(); it++) {
       if (*it == app)
          break;
}
return it;  // return found iterator, or 'end' if not found. 

注意!=而不是= 。

此外，最好在 for 循環之外返回，否則編譯器會抱怨您可能沒有從 function 返回值。