如何实现find_if和remove_if

问题描述

你好.
这是我的代码:

Hello.
Here is my code :

#include <iostream>
#include <algorithm>
#include <vector>
#include <string>

using namespace std;

struct Person
{
        string Name;
        string ID;
};

class mainClass
{
        private :
                vector <Person> Vector;

        public :
                mainClass() { }
                void storeVector();
                void displayVector();
                void findID();
                void removeID();
};

void mainClass :: storeVector()
{
        Person Obj1;
        Obj1.Name = "Tapas";
        Obj1.ID = "1";
        Vector.push_back(Obj1);

        Person Obj2;
        Obj2.Name = "Ashok";
        Obj2.ID = "2";
        Vector.push_back(Obj2);

        Person Obj3;
        Obj3.Name = "Arnab";
        Obj3.ID = "3";
        Vector.push_back(Obj3);

        Person Obj4;
        Obj4.Name = "Sayantan";
        Obj4.ID = "4";
        Vector.push_back(Obj4);

        Person Obj5;
        Obj5.Name = "Mrinal";
        Obj5.ID = "5";
        Vector.push_back(Obj5);
}

void mainClass :: displayVector()
{
        for (vector <Person> :: iterator it = Vector.begin(); it != Vector.end(); it++)
        {
                cout << "  Name : " << it->Name << ", ID : " << it->ID << endl;
        }
}

void mainClass :: findID()
{
        string ID;

        cout << "  Enter the ID to find : ";
        cin >> ID;

        vector <Person> :: iterator it;

        for (it = Vector.begin(); it != Vector.end(); it++)
        {
                if (ID == it->ID)
                {
                        break;
                }
        }

        if (it != Vector.end())
        {
                cout << "  Specified ID found." << endl;
                cout << "  Name : " << it->Name << ", ID : " << it->ID << endl;
        }
        else
        {
                cout << "  Specified ID not found." << endl;
        }
}

void mainClass :: removeID()
{
        string ID;

        cout << "  Enter the ID to remove : ";
        cin >> ID;

        vector <Person> :: iterator it;

        for (it = Vector.begin(); it != Vector.end(); it++)
        {
                if (ID == it->ID)
                {
                        break;
                }
        }

        if (it != Vector.end())
        {
                cout << "  Specified ID found." << endl;
                cout << "  Name : " << it->Name << ", ID : " << it->ID << endl;
                Vector.erase(it);
        }
        else
        {
                cout << "  Specified ID not found." << endl;
        }
}

int main()
{
        mainClass Obj;

        Obj.storeVector();
        Obj.displayVector();
        Obj.findID();
        Obj.removeID();
        Obj.displayVector();

        return 0;
}

这段代码还可以，并且可以提供所需的输出，但是我想使用算法标头的find/find_if和remove_if函数来实现findID()和removeID()函数.是否有可能?如果可能的话，我该如何实施呢?请帮忙.

This code is okay and gives desired output, but I want to implement findID() and removeID() function using find/find_if and remove_if function of algorithm header. Is it possible? If possible, then how can I implement it? Please help.

推荐答案

#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <functional>
#include <iterator>

using namespace std;

struct Person
{

	string Name;
	string ID;
};

class mainClass
{
	private :
		vector <Person> Vector;

	public :
		mainClass() { }
		void storeVector();
		void displayVector();
		void findID();
		void removeID();

		friend ostream & operator << (ostream &, const Person &);
};

struct IDnumber : public binary_function <Person, string, bool>
{
	bool operator () ( const Person &Obj, const string &ID ) const
	{
    		return (Obj.ID == ID);
	}
};

ostream & operator << (ostream &stream, const Person &Obj)
{
	return stream << "  Name : " << Obj.Name << ", ID : " << Obj.ID;
}

void mainClass :: storeVector()
{
	Person Obj1;
	Obj1.Name = "Tapas";
	Obj1.ID = "1";
	Vector.push_back(Obj1);

	Person Obj2;
	Obj2.Name = "Ashok";
	Obj2.ID = "2";
	Vector.push_back(Obj2);

	Person Obj3;
	Obj3.Name = "Arnab";
	Obj3.ID = "3";
	Vector.push_back(Obj3);

	Person Obj4;
	Obj4.Name = "Sayantan";
	Obj4.ID = "4";
	Vector.push_back(Obj4);

	Person Obj5;
	Obj5.Name = "Mrinal";
	Obj5.ID = "5";
	Vector.push_back(Obj5);
}

void mainClass :: displayVector()
{
	copy(Vector.begin(), Vector.end(), ostream_iterator <Person> (cout, "\n"));
}

void mainClass :: findID()
{
	string ID;

	cout << endl;
	cout << "  Enter the ID to find : ";
	cin >> ID;

	vector <Person> :: iterator it;

	it = find_if(Vector.begin(), Vector.end(), bind2nd(IDnumber(), ID));

	if (it != Vector.end())
	{
		cout << "  Specified ID found." << endl;
		cout << "  Name : " << it->Name << ", ID : " << it->ID << endl;
	}
	else
	{
		cout << "  Specified ID not found." << endl;
	}
}

void mainClass :: removeID()
{
	string ID;

	cout << endl;
	cout << "  Enter the ID to remove : ";
	cin >> ID;

	vector <Person> :: iterator it;

	it = find_if(Vector.begin(), Vector.end(), bind2nd(IDnumber(), ID));

	if (it != Vector.end())
	{
		cout << "  Specified ID found." << endl;
		cout << "  Name : " << it->Name << ", ID : " << it->ID << endl;
		Vector.erase(it);
		cout << "  Data successfully deleted." << endl << endl;
	}
	else
	{
		cout << "  Specified ID not found." << endl;
	}
}

int main()
{
	mainClass Obj;

	Obj.storeVector();
	Obj.displayVector();
	Obj.findID();
	Obj.removeID();
	Obj.displayVector();

	return 0;
}

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