Vector series in practice c ++ -- use std: find and std: find_if algorithms for vector (custom class)

Vector series in practice c ++ -- use std: find and std: find_if algorithms for vector (custom class)

Previously, my blog talked about some usage of std: find and std: find _ if, but not about the custom class stored in the vector. How to Use std:: find and std: find_if?

First define a class:

class Item{private:    std::string  m_ItemId;    int m_Price;    int m_Count;public:    Item(std::string id, int price, int count):        m_ItemId(id), m_Count(count), m_Price(price){}    int getCount() const {        return m_Count;    }    std::string getItemId() const {        return m_ItemId;    }    int getPrice() const {        return m_Price;    }    bool operator==(const Item & obj2) const    {        if(this->getItemId().compare(obj2.getItemId()) == 0)            return true;        else            return false;    }};std::vector
  
    getItemList(){    std::vector
   
     vecOfItems ;    vecOfItems.push_back(Item("D121",100,2));    vecOfItems.push_back(Item("D122",12,5));    vecOfItems.push_back(Item("D123",28,6));    vecOfItems.push_back(Item("D124",8,10));    vecOfItems.push_back(Item("D125",99,3));    return vecOfItems;}
   
  

Next we use the std: find algorithm:

Int main () {std: vector
  
   
VecOfItems = getItemList (); std: vector
   
    
: Iterator it; it = std: find (vecOfItems. begin (), vecOfItems. end (), Item ("D123", 99, 0); if (it! = VecOfItems. end () std: cout <"Found with Price:" <it-> getPrice () <"Count:" <it-> getCount () <std: endl; else std: cout <"Item with ID: D126 not Found" <std: endl; return 0;} // output: found with Price: 28 Count: 6
   
  

However, if = is not available, we can use find_if to solve the problem:
Add function:

bool priceComparision(Item & obj, int y){    if(obj.getPrice() == y)        return true;    else        return false;}

This is the case:

#include
  
   #include
   
    #include
    
     #include#include
     
      using namespace std;class Item{private:    std::string  m_ItemId;    int m_Price;    int m_Count;public:    Item(std::string id, int price, int count) :        m_ItemId(id), m_Count(count), m_Price(price) {}    int getCount() const {        return m_Count;    }    std::string getItemId() const {        return m_ItemId;    }    int getPrice() const {        return m_Price;    }    bool operator==(const Item & obj2) const    {        if (this->getItemId().compare(obj2.getItemId()) == 0)            return true;        else            return false;    }};bool priceComparision(Item & obj, int y){    if (obj.getPrice() == y)        return true;    else        return false;}std::vector
      
        getItemList(){ std::vector
       
         vecOfItems; vecOfItems.push_back(Item("D121", 100, 2)); vecOfItems.push_back(Item("D122", 12, 5)); vecOfItems.push_back(Item("D123", 28, 6)); vecOfItems.push_back(Item("D124", 8, 10)); vecOfItems.push_back(Item("D125", 99, 3)); return vecOfItems;}int main(){ std::vector
        
          vecOfItems = getItemList(); std::vector
         
          ::iterator it; it = std::find_if(vecOfItems.begin(), vecOfItems.end(), std::bind(priceComparision, std::placeholders::_1, 28)); if (it != vecOfItems.end()) std::cout << "Item Price ::" << it->getPrice() << " Count :: " << it->getCount() << std::endl; else std::cout << "Item not Found" << std::endl; return 0;}
         
        
       
      
     
    
   
  

Finally, you can use the lambda expression:

std::vector
  
    vecOfItems = getItemList();std::vector
   
    ::iterator it;it = std::find_if(vecOfItems.begin(), vecOfItems.end(), [](Item const& obj){        return obj.getPrice() == 28;    } );if(it != vecOfItems.end())    std::cout<<"Item Price ::"<
    
     getPrice()<<" Count :: "<
     
      getCount()<