Programiranje u C++-u - pitanja i odgovori

Ovakav kod ali sa vektorom umjesto liste, radi perfektno. Ovaj izbacuje hrpu errora, u cemu je problem? (sortiranje listi opcenito nisam skuzio, pa ako netko moze neki primjer napisati)

#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <list>
using namespace std;

bool ascending(int x, int y);
bool descending(int x, int y);
void output(list<int>my_list);

int main()
{
    list<int> my_list;
    int value;
   
    while(1)
    {
        cout << "Enter a positive number or -1 to quit:" << endl;
        cin >> value;
        if(value==-1)
            break;
        else
            my_list.push_back(value);              
    }
   
    system("CLS");
    cout << "You have entered the following numbers:" << endl;
    output(my_list);
   
    cout << "After sorting:" << endl;
    sort(my_list.begin(), my_list.end(),  ascending);
    output(my_list);
   
   
    system("pause");
    return 0;   
}

bool ascending(int x, int y)
{
    return x < y;    
}

bool descending(int x, int y)
{
    return x > y;    
}

void output(list<int>my_list)
{
    for(list<int>::iterator it=my_list.begin(); it != my_list.end(); it++)
    {
        cout << *it <<"\t";                         
    }  
    cout << endl; 
}

Radio sam po ovome http://www.learncpp.com/cpp-tutorial/813-friend-functions-and-classes/ ali sam ocito zeznuo negdje. Na pocetku koda je napisan zadatak.

/* Product Inventory Project - Create an application which manages an inventory
  of products. Create a product class which has a price, id, and quantity on
  hand. Then create an inventory class which keeps track of various products
  and can sum up the inventory value. */
 
#include <iostream>
#include <vector>
#include <cstdlib>
#include <string>
using namespace std;

class Product
{
    private:
        string name;
        float price;
        int ID;
        int quantity;     
   
    public:
        Product (string name, float price, int ID, int quantity)
        {
            this->name = name;
            this->price = price;
            this->ID = ID;
            this->quantity = quantity;   
        }
       
        string get_name() {return name;}
        float get_price() {return price;}
        int get_ID() {return ID;}
        int get_quantity() {return quantity;}
       
        friend class Inventory;
};

class Inventory
{
    public:
       Inventory() { cout << "Building an Inventory." << endl; }
        ~Inventory() { cout << "Destroying an Inventory." << endl; }
          
        Product access;
        void get_data(Product &access)
        {
            cout << access.get_ID() <<" " << access.get_name() << " @ " <<
                access.get_price() << " " << access.get_quantity() << endl;   
        }     
};

//---------------------------------------------------------------------------//

int main()
{
    vector<Product> my_vector;
    string name;
    float price;
    int ID;
    int quantity;
    char input;
   
    while(1)
    {
        cout << "Enter the name of the product:" << endl;
        getline(cin, name);
       
        cout << "Enter " << name << " price:" << endl;
        cin >> price;
       
        cout << "Enter " << name << " ID number: " << endl;
        cin >> ID;
       
        cout << "Enter " << name << " quantity:" << endl;
        cin >> quantity;
       
        Product temp(name, price, ID, quantity);
        my_vector.push_back(temp);
       
        cout << "Enter another product <Y/N>?" << endl;
        cin >> input;
        if(input == 'n' || input == 'N')
           break;
    }
   
    Inventory my_inventory;
    for(vector<Product>::iterator it=my_vector.begin(); it != my_vector.end(); it++)
    {
       my_inventory.get_data(access);
    }  
   
    system("pause");
    return 0;   
}

Ovo su greske koje javlja:

In constructor `Inventory::Inventory()' no matching function for call to `Product::Product()'
In function `int main()' `access' undeclared (first use this function)

Hvala.

@Rattner :: što se tiče ove druge nejasnoće

   Copy-Paste i kompiliraj - radi , objašnjenje u komentarima

/* Product Inventory Project - Create an application which manages an inventory
  of products. Create a product class which has a price, id, and quantity on
  hand. Then create an inventory class which keeps track of various products
  and can sum up the inventory value. */

#include <iostream>
#include <vector>
#include <cstdlib>
#include <string>
using namespace std;

class Product
{
    private:
        string name;
        float price;
        int ID;
        int quantity;

    public:

        // vidi u Inventory za objasnjenje
        Product() {}
        // linije prije ove

        Product (string name, float price, int ID, int quantity)
        {
            this->name = name;
            this->price = price;
            this->ID = ID;
            this->quantity = quantity;
        }

        string get_name() {return name;}
        float get_price() {return price;}
        int get_ID() {return ID;}
        int get_quantity() {return quantity;}

        friend class Inventory;
};

class Inventory
{
    public:
       Inventory() { cout << "Building an Inventory." << endl; }
        ~Inventory() { cout << "Destroying an Inventory." << endl; }

        /* iniciras Produkt s nedefiniranim
        konstruktorom Product()
        gore ti je definirano :::::::::::::::::::::::::::::::::
        Product (string name, float price, int ID, int quantity)
        Gore onda dodaj prazan konstruktor iako ti je line__::Product access; nepotrebno*/
        Product access;
        void get_data(Product &access)
        {
            cout << access.get_ID() <<" " << access.get_name() << " @ " <<
                access.get_price() << " " << access.get_quantity() << endl;
        }
};

//---------------------------------------------------------------------------//

int main()
{
    vector<Product> my_vector;
    string name;
    float price;
    int ID;
    int quantity;
    char input;

    while(1)
    {
        cout << "Enter the name of the product:" << endl;
        getline(cin, name);

        cout << "Enter " << name << " price:" << endl;
        cin >> price;

        cout << "Enter " << name << " ID number: " << endl;
        cin >> ID;

        cout << "Enter " << name << " quantity:" << endl;
        cin >> quantity;

        Product temp(name, price, ID, quantity);
        my_vector.push_back(temp);

        cout << "Enter another product <Y/N>?" << endl;

        cin >> input;
       
        /* flushaj cin zbog getline-a
        inace ti preskace liniju
        zakomentiraj ovo dolje pa vidi*/
        cin.ignore(256 , '\n' );
        cin.clear();

        if(input == 'n' || input == 'N')
           break;
    }

    Inventory my_inventory;
    for(vector<Product>::iterator it=my_vector.begin(); it != my_vector.end(); it++)
    {
       /*predajes Product u Inventory
         znaci u ovom slucaju *it*/
       //my_inventory.get_data(access);

         my_inventory.get_data(*it);
    }

    system("pause");
    return 0;
}

/*ako trebas cisti C onda samo
zamijeni ispis sa stdio.h*/
#include<iostream>

using namespace std;

int main()
{

double a , b;

// prije
a = 9.1234;
b = 398.497654;

cout.precision(9);
cout<< a << "  " << b << endl;
cout<< a+b << endl;

a = ((int)(a * 100)) * 0.01;
b = ((int)(b * 100)) * 0.01;

//poslije
cout<< a << "  " << b << endl;
cout<< a+b << endl;


return 0;
}

zadnji delete[] x je van petlje.

#include <iostream>
using namespace std;

int main() {
    int **x, i, j, REDAK = 5, STUPAC = 3;

    x = new int*[REDAK];
    for (i = 0; i < REDAK; i++)
       x[i] = new int[STUPAC];

    for(i = 0; i < REDAK; i++){
       for (j = 0; j < STUPAC; j++) {
          x[i][j] = (j + 1);
          cout << x[i][j] << "\t";
       }
       cout << endl;
    }
    for (i = 0; i < REDAK; i++)
       delete [] x[i];
    delete [] x;
    return 0;
}

Moze mi neko reci par stranica slicnih z-treningu?(da mogu uploadovat rjesenje pa da provjeri i to)

Sto je ovdje krivo? Radim po Demistificiranom C++ (2. izdanje) i isti taj kod je u knjizi.

Izbacuje mi ovu gresku:

day.cpp: In function ‘int main()’:
day.cpp:17: warning: deprecated conversion from string constant to ‘char*’
day.cpp:17: warning: deprecated conversion from string constant to ‘char*’
day.cpp:17: warning: deprecated conversion from string constant to ‘char*’
day.cpp:17: warning: deprecated conversion from string constant to ‘char*’
day.cpp:17: warning: deprecated conversion from string constant to ‘char*’
day.cpp:17: warning: deprecated conversion from string constant to ‘char*’
day.cpp:17: warning: deprecated conversion from string constant to ‘char*’
day.cpp:29: warning: deprecated conversion from string constant to ‘char*’
day.cpp:29: warning: deprecated conversion from string constant to ‘char*’
day.cpp:29: warning: deprecated conversion from string constant to ‘char*’
day.cpp:29: warning: deprecated conversion from string constant to ‘char*’
day.cpp:29: warning: deprecated conversion from string constant to ‘char*’
day.cpp:29: warning: deprecated conversion from string constant to ‘char*’
day.cpp:29: warning: deprecated conversion from string constant to ‘char*

#include <iostream>
using namespace std;

int main() {
   
    char *dani[] = {
      
       "Ponedeljak",
       "utorak",
       "srijeda",
       "cetvrtak",
       "petak",
       "subota",
       "nedelja",
      
    };
   
    char *days[] = {
      
       "sunday",
       "monday",
       "tuesday",
       "wednesday",
       "thursday",
       "friday",
       "saturday"
      
    };
   
    for (int i = 0; i < 7; i++) {
      
       dani[i] = days[i];
      
    }
   
    return 0;
   
}

Stavi const prije chara i radit će ti.

#include <iostream>
using namespace std;

int main() {
  
  const  char *dani[] = {
     
       "Ponedeljak",
       "utorak",
       "srijeda",
       "cetvrtak",
       "petak",
       "subota",
       "nedelja",
     
    };
  
 const   char *days[] = {
     
       "sunday",
       "monday",
       "tuesday",
       "wednesday",
       "thursday",
       "friday",
       "saturday"
     
    };
  
    for (int i = 0; i < 7; i++) {
     
       dani[i] = days[i];
     
    }

    for (int i = 0; i < 7; i++) {
     
       cout<< dani[i]  << endl;
     
    }

  
    return 0;
  
}

Teško pitanje, kada neko generalno pita koji jezik da uči, uvjek se svede na C++ ili C#/Javu. Nećeš pogrješiti bilo koji da uzmeš, ali moja preporuka bi bila da ideš na C# ili Javu, ako nećeš biti ovistan o .NET-u, jel. Oni su strogo OO jezici, tako će, vjerovatno, bolje i brže naučiti OO paradigmu. Tako da bi moj prjedlog bio - C#.
Tracer ti je tamo profesor, čekaj njega.

EDIT: C::B je za C++, a ne za C#.

Hvala na prijedlogu . Koliko sam vidio u 6 semestru imam C++ ,ali da krenem učiti bilo koji jezik mislim da će biti odlična podloga za nastaviti i na faksu a i za ubuduće. 

Još ću pričekati Tracera da čujem njegov savjet,a onda krećem u skupljanje materijala i učenje :) 

EDIT:

Hvala. Još sam tražio i nikako da nađem. Ovo je super sređeno i sortirano. Sve pohvale :) Vidim da se kolegij nemože upisati bez odslušanog Programiranja pa ću i tamo malo zaviriti . Hvala na savjetima.

Možeš li mi to malo pojasniti, to da je mačiji kašalj?

Microsoft je zapustio MFC to je istina, ali to je i bilo radi toga da se pređe na .NET, sada sa WinRT frameworkom C++ je bolji izbor od drugih .NET jezika. Koliko znam, a i u Mreži je bio članak o tome, u novom .NET-u, Microsoft bi trebao osvježiti C++.

Bogata paleta nema šta, ali ti si taj alat, ako se ne varam, platio 1200 $? Skinuo sam ga trial, no što dobijem sa Turbo C++ 2006 Express od toga?

Ja sam taj alat platio nakon što sam odlučio da od toga zarađujem. Do tada....

Inače, postoji i starter edition koji je nekih 100-150$. Komercijalna verzija kojom možete zarađivati. A može se kupiti i akademska licenca. Mislim da je svega par desetaka eura. No opet kažem, ako to koristite samo za učenje i tu i tamo neki sitni programčić ne vjerujem da će vas itko ikad gnjaviti.