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c++利用stl set_difference對車輛進出區(qū)域進行判定

更新時間：2017年03月13日 22:32:28 作者：Leckun

這篇文章主要介紹了set_difference，用于求兩個集合的差集，結(jié)果集合中包含所有屬于第一個集合但不屬于第二個集合的元素,需要的朋友可以參考下

核心代碼

#include <iostream>  
#include <vector>  
#include <string>  
#include <algorithm>  
using namespace std;  
struct _AREA_VECTOR_STRUCT 
{ 
  int nAreaType;//區(qū)域類型 
  int nAreaID;//區(qū)域ID 
}; 
 
void CtestDlg::OnBnClickedButton2() 
{ 
  vector<_AREA_VECTOR_STRUCT> structAreaHistory;//車輛上一次所在區(qū)域 
  vector<_AREA_VECTOR_STRUCT> structAreaNow;//車輛本次所在區(qū)域 
  vector<_AREA_VECTOR_STRUCT> OutStructAreaVector;//輸出區(qū)域 
 
  _AREA_VECTOR_STRUCT structVehicle; 
 
  //模擬上一次車輛所在的區(qū)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); 
 
  //模擬本次車輛所在的區(qū)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，先按區(qū)域類型排序，再按區(qū)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，結(jié)果為離開區(qū)域的集合（出區(qū)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 
 
  //反過來求差，結(jié)果為新進入的區(qū)域集合（新進區(qū)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("重新進"); 
  } 
}

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