vecotr working for .erase but not .pop_back

[maharris]

in reference to:userMain.BookingsVector.pop_back(userMain.BookingsVector.begin()+book_name_select);


Error 2 error C2660: 'std::vector<_Ty>::pop_back' : function does not take 1 arguments f:\project3.1\project3.1\project3.1.cpp 222 1 project3.1

any suggestions?

class Bookings{
public:
	Bookings();
	string name;
	void display_name();
};
class Users{
public:
	Users();
	vector<Bookings> BookingsVector;
	string username;
};
Bookings::Bookings(){
};

Users::Users(){
};
int main(){

Bookings::display_name{
cout<<name<<endl;
};


case 2:{

					std::cout<<"Welcome to the edit booking menu!"<<endl
					<<"select booking"<<endl;
					
	
	while(loop <userMain.BookingsVector.size()){
	
		cout<<"["<<loop<<"]";
		userMain.BookingsVector[loop].display_name();
	
	
	loop=loop+1;}
	cin>>book_name_select;
	userMain.BookingsVector.pop_back(userMain.BookingsVector.begin()+book_name_select);

[ciphermagi]

http://www.cplusplus.com/reference/stl/vector/pop_back/

As you will see above, pop_back doesn't accept any arguments, instead it just deletes the very last element in a container, no matter where the iterator is, or in your case where the pointer arithmetic puts it.

[Texan40]

I'm just guessing he meant to use push_back() instead of pop_back() since he's taking user input right before the call...

[ciphermagi]

He's using pointer arithmetic on that input, though, which indicates that he's trying to delete a certain element based on the beginning of the vector plus however many entries the user indicates, potentially by choosing a book that was displayed in the loop for displaying the names of the books already contained in the vector.

[Texan40]

Sometimes I feel like a goat staring at a watch...

[maharris]

cipher is right, i'm trying to have the user enter the selected book out of the ones displayed then it deletes that specific booking, when i do .erase it erases all of the bookings, not just the user entered one.

is there another function of vector i can use? or is there a way to do what i said above?

[maharris]

when i do userMain.BookingsVector.begin()+book_name_select;
userMain.BookingsVector.pop_back;

EDIT:
it deletes all of them from displaying(caught that it still is viable to enter).....

class Bookings{
public:
	Bookings();
	string name;
	void display_name();
};
class Users{
public:
	Users();
	vector<Bookings> BookingsVector;
	string username;
};
Bookings::Bookings(){
};

Users::Users(){
};
int main(){

Bookings::display_name{
cout<<name<<endl;
};


case 2:{

					std::cout<<"Welcome to the edit booking menu!"<<endl
					<<"select booking"<<endl;
					
	
	while(loop <userMain.BookingsVector.size()){
	
		cout<<"["<<loop<<"]";
		userMain.BookingsVector[loop].display_name();
	
	
	loop=loop+1;}
	cin>>book_name_select;
userMain.BookingsVector.begin()+book_name_select;
	userMain.BookingsVector.pop_back;

[maharris]

bump

[LB]

.erase() let's you specify a position to erase via an iterator:
MyVector.erase(MyVector.begin()+PositionToErase);
http://www.cplusplus.com/reference/stl/vector/erase/

[maharris]

when i do that it is still viable to enter the position, but the display doesnt show the
[0] bookname
[1] bookname2

etc.

it just shows welcome to the edit booking menu, please select booking with no options even though you can still enter a position

[maharris]

bump

[clanmjc]

Because the vector is now empty? Or because loop < size is not longer true? I'm not sure what you mean.

[maharris]

the vector isnt empty, it isnt the loop<size, it just doesnt display the bookings that are in there once you remove one booking; however it is still viable to enter 0,1,2....etc.

[maharris]

okay i figured out if you remove the booking, then add a new one, it will show t newly added booking, but not the previous ones. i'm confused

[maharris]

bump

[ciphermagi]

Your code is terribly hard to read. That's why nobody wants to help you with it. You need an iterator, and the User class is useless.

http://www.cplusplus.com/reference/std/iterator/

#include <iostream>
#include <vector>

class Bookings{
public:
    Bookings(){}; // Empty constructors should be defined in-line.
    ~Bookings(); // Define a constructor, define a destructor.
    string name;
    void display_name();
};

void Bookings::display_name() // Put a return type on your functions
                              // and put them outside of main.
{
    std::cout << name << endl;
}

int main()
{
    vector<Bookings> BookingsVector; // Vector in main.
    vector<Bookings>::iterator it; // Iterator for the vector.

    std::cout << "Welcome to the edit booking menu!" << endl << "select booking" << endl;
    for (int i = 0; i < BookingsVector.size(); ++i){ // For loop does what your
                                                     // while loop does, but cleaner.
        std::cout << "[" << i << "]"; 
        BookingsVector[i].display_name();
    }
    std::cin >> book_name_select; // Get user input.
    it = BookingsVector.begin()+book_name_select; // Set the iterator.
    it.erase(); // Erase the record.
}