Search in vector

[Hashimatsu]

I want to add a search function to search my vector for a text string.

I tried this:

#include <vector>
#include <algorithm> 

....

vector<Bar>Foobar;

string Foo;
getline(cin, Foo);

....

vector<Bar>::iterator Baz;

Baz = find (Foobar.begin(), Foobar.end(), Foo);

cout << "Result: " << *Baz << endl;

I get error:

error: no match for 'operator=' in 'Baz = std::find
and

stl_iterator.h line 669

note: candidates are: __gnu_cxx::__normal_iterator<std::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >& __gnu_cxx::__normal_iterator<std::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basi|

Can someone tell me what I'm doing wrong?

Thanks in advance

[vlad from moscow]

Your vector is defined as having type Bar but you are trying to compare an object of type Bar with a string. If there is no such an overload operator == in the class then you can not do that.

[Hashimatsu]

I'm not sure if I understand what you're telling me... =)

This is the code:

#include <iostream>
#include <vector>
#include <windows.h>//För att använda system "cls" och sleep
#include <limits>   //För att använda numeric_limits
#include <algorithm>

using namespace std;

class Film
{
    public:

        // Deklarerar variablerna för de data som behövs
        string Titel;
        string Media;


        // Denna funktion skriver ut filmen på skärmen
        void skrivFilm()
        {
            cout << endl;
            cout << "Titel: " << Titel << endl; // Skriver ut filmens titel
            cout << "Media: " << Media << endl; // Skriver ut filmens media
        }
};

int main()
{
    setlocale(LC_ALL, "swedish");   // Denna funktion låter mig använda svenska

    vector<Film> Arkiv;             // Skapa en vector av typen Film

    char menyVal;                   // Denna variabel håller reda på vilket val användaren anger i huvudmenyn
    Film nyFilm;                    // För att skapa en film behöver vi ett objekt att spara den i

    do
    {

    system("cls"); // Se till att rensa skärmen

    cout << "    ** ARKIV **    " << endl;
    cout << "*******************" << endl;
    cout << "1: Ny film"          << endl;
    cout << "2: Radera film"      << endl;
    cout << "3: Sök efter film"   << endl;
    cout << "4: Visa alla"        << endl;
    cout << "0: Avsluta"          << endl;
    cout << "___________________" << endl;
    cout << "Ange val: ";

    cin >> menyVal;
    cin.ignore( numeric_limits <streamsize>::max(), '\n' );


    switch(menyVal)
        {
            case '1':
                {
                    system("cls");
                    cout << "\n\n1: Ny film";
                    Sleep(1000);
                    cout << endl << endl;
                    // Vi ger objektets titel-variabel ett värde
                    cout << "Ange filmens Titel: ";
                    getline(cin, nyFilm.Titel);
                    cout << endl;

                    // Vi ger objektets media-variabel ett värde
                    cout << "Ange filmens Media: ";
                    getline(cin, nyFilm.Media);
                    cout << endl;

                    // Vi lägger vårt filmobjekt i vektorn
                    Arkiv.push_back( nyFilm );

                    break; // Undvik fall-through
                }
            case '2':
                {
                    break;
                }
            case '3':                                             // <---THIS IS THE PROBLEM
                {
                    string objekt;
                    getline(cin, objekt);

                    vector<Film>::iterator it;

                    it = find (Arkiv.begin(), Arkiv.end(), objekt);

                    cout << "Filmen du sökte efter: " << *it << endl;

                    break;
                }
            case '4':
                {
                    system("cls");

                    for(int i=0; i<Arkiv.size(); i++)   // Räkna upp alla filmer i Arkiv
                    {
                        Arkiv[i].skrivFilm();           // Skriv ut dem med hjälp av funktionen skrivFilm();
                    }

                    cout << "\n\nTryck på ENTER för Huvudmeny.";
                    cin.ignore();
                    break;
                }
            case '0':
                {
                    break;
                }
            default :   cout << "Felaktigt val, försök igen." << endl;
                        Sleep(1000);
                        system("cls");
        }
    }
    while( menyVal != '0');

}

Hope it helps more than the "example" I posted before...

[vlad from moscow]

You can not compare directly Film with string because they have different types.

If you want to compare member Titel of an object of class Film with a string you can write

it = find_if(Arkiv.begin(), Arkiv.end(), 
                [&] ( const Film &f )
                {
                   return ( f.Titel == objekt);
                } );

provided that your compiler supports lambda-expressions.
Otherwise you have to write a functional object.

[Hashimatsu]

This following block gives me an error:

            case '3':
                {
                    string objekt;
                    getline(cin, objekt);

                    vector<Film>::iterator it

                    it = find_if(Arkiv.begin(), Arkiv.end(),[&] ( const Film &f )
                    {
                        return ( f.Titel == objekt);
                    }

                    break;
                }

Error:

error: expected initializer before 'it'

[Hashimatsu]

Please give me a hint? Or tell me if I need to specify the problem...

[vlad from moscow]

I do not see a semicolon in the very end of line

vector<Film>::iterator it

[Hashimatsu]

Now I got

            case '3':
                {
                    string objekt;
                    getline(cin, objekt);

                    vector<Film>::iterator it;

                    it = find_if(Arkiv.begin(), Arkiv.end(),[&] ( const Film &f );
                    {
                        return ( f.Titel == objekt);
                    }

                    break;
                }

and get error

error: expected primary-expression before '[' token

error: expected primary-expression before ']' token

error: expected primary-expression before 'const'

error: 'f' was not declared in this scope

[vlad from moscow]

Please try to rewrite the code as i showed you.

Why did you place a semicolon here?!

it = find_if(Arkiv.begin(), Arkiv.end(),[&] ( const Film &f );