stl set_difference c++利用stl set_difference对车辆进出区域进行判定

#include <iostream>  
#include <vector>  
#include <string>  
#include <algorithm>  
using namespace std;  
struct _AREA_VECTOR_STRUCT 
{ 
  int nAreaType;//区域类型 
  int nAreaID;//区域ID 
}; 
 
void CtestDlg::OnBnClickedButton2() 
{ 
  vector<_AREA_VECTOR_STRUCT> structAreaHistory;//车辆上一次所在区域 
  vector<_AREA_VECTOR_STRUCT> structAreaNow;//车辆本次所在区域 
  vector<_AREA_VECTOR_STRUCT> OutStructAreaVector;//输出区域 
 
  _AREA_VECTOR_STRUCT structVehicle; 
 
  //模拟上一次车辆所在的区域集合 
  structVehicle.nAreaType = 2; 
  structVehicle.nAreaID = 0x45; 
  structAreaHistory.push_back(structVehicle); 
  structVehicle.nAreaID = 0x7A; 
  structAreaHistory.push_back(structVehicle); 
  structVehicle.nAreaID = 0x88; 
  structAreaHistory.push_back(structVehicle); 
 
  structVehicle.nAreaType = 3; 
  structVehicle.nAreaID = 0x55; 
  structAreaHistory.push_back(structVehicle); 
  structVehicle.nAreaID = 0x88; 
  structAreaHistory.push_back(structVehicle); 
 
  //模拟本次车辆所在的区域集合 
  structVehicle.nAreaType = 2; 
  structVehicle.nAreaID = 0x88; 
  structAreaNow.push_back(structVehicle); 
  structVehicle.nAreaID = 0x45; 
  structAreaNow.push_back(structVehicle); 
  structVehicle.nAreaID = 0x11; 
  structAreaNow.push_back(structVehicle); 
 
  structVehicle.nAreaType = 3; 
  structVehicle.nAreaID = 0x55; 
  structAreaNow.push_back(structVehicle); 
 
  //排序，先按区域类型排序，再按区域ID排序 
  sort(structAreaHistory.begin(), structAreaHistory.end(),[] (_AREA_VECTOR_STRUCT structArea1, _AREA_VECTOR_STRUCT structArea2)->bool 
  { 
    if(structArea1.nAreaType != structArea2.nAreaType) 
      return structArea1.nAreaType < structArea2.nAreaType; 
    else 
      return structArea1.nAreaID < structArea2.nAreaID; 
  }); 
  sort(structAreaNow.begin(), structAreaNow.end(),[] (_AREA_VECTOR_STRUCT structArea1, _AREA_VECTOR_STRUCT structArea2)->bool 
  { 
    if(structArea1.nAreaType != structArea2.nAreaType) 
      return structArea1.nAreaType < structArea2.nAreaType; 
    else 
      return structArea1.nAreaID < structArea2.nAreaID; 
  }); 
 
  int a = 0; 
 
  //求差，结果为离开区域的集合（出区域） 
  set_difference(structAreaHistory.begin(), structAreaHistory.end(), structAreaNow.begin(), structAreaNow.end(), back_inserter(OutStructAreaVector), 
    [](_AREA_VECTOR_STRUCT structArea1, _AREA_VECTOR_STRUCT structArea2)->bool 
  { 
    if(structArea1.nAreaType != structArea2.nAreaType) 
      return structArea1.nAreaType < structArea2.nAreaType; 
    else 
      return structArea1.nAreaID < structArea2.nAreaID; 
  }); 
 
  if(OutStructAreaVector.size() != 0) 
  { 
    TRACE("出"); 
  } 
 
  OutStructAreaVector.clear();//先清空 
 
  //反过来求差，结果为新进入的区域集合（新进区域） 
  set_difference(structAreaNow.begin(), structAreaNow.end(), structAreaHistory.begin(), structAreaHistory.end(), back_inserter(OutStructAreaVector), 
    [](_AREA_VECTOR_STRUCT structArea1, _AREA_VECTOR_STRUCT structArea2)->bool 
  { 
    if(structArea1.nAreaType != structArea2.nAreaType) 
      return structArea1.nAreaType < structArea2.nAreaType; 
    else 
      return structArea1.nAreaID < structArea2.nAreaID; 
   
  }); 
 
  if(OutStructAreaVector.size() != 0) 
  { 
    TRACE("重新进"); 
  } 
}