reading a file in alphabetical order

[rezy3312]

#include <iostream>
#include <string> 
#include <fstream> // to read file
#include <algorithm> // to use sort

using namespace std;

const int SIZE = 100;

struct Movie // movie information
{
	string name[SIZE];
	int year;
	double price;
};


int main()
{

	cout << "The movies that we have on the list are" << endl;
	cout << "-----------------" << endl;

	ifstream listfile;

	listfile.open("Movie.txt");

	
	Movie list; // struct object


	if (listfile.is_open())
	{
		string name;
		string temp;

		while (getline(listfile, name)) 
		{
			cout << name << endl;

		}

		
	}

	else
		cout << "unable to read file" << endl;
	
	listfile.close();

	system ("pause");
	return 0;
}



		

[rezy3312]

i am trying to read the file in alphabetical order but i wanted to use the sort function i found online but i can't understand it can someone explain it to me please.

sort (name.begin(), name.end(), myobject);


for example the text reads names of movies that are out of order by title how would you use the sort function.

thank you.

[Thomas1965]

A common procedure would be to read all the data into a vector and sort the vector.
Why do you want to store 100 names in a movie ?

struct Movie // movie information
{
	string name[SIZE];
	int year;
	double price;
};

How does your input file look ?

[AbstractionAnon]

Line 12: Your dimension is in the wrong place. A movie doesn't have 100 names. By using a vector, you don't need to explicitly dimension list.

Line 37-41: You're reading name from the file, but not putting it anywhere. Need to know the format of the file in order to know how to read year and price.

#include <iostream>
#include <string> 
#include <fstream> // to read file
#include <algorithm> // to use sort
#include <vector>
using namespace std;

struct Movie // movie information
{   string name;
	int year;
	double price;
};

bool compare_movies (const Movie & a, const Movie & b)
{   return a.name < b.name;
}

int main()
{   vector<Movie>   list;   //  Movies are stored here
    string          name;
    int             count = 0; 
        
    cout << "The movies that we have on the list are" << endl;
	cout << "-----------------" << endl;
	ifstream listfile;
	listfile.open("Movie.txt");
	if (! listfile.is_open())
	{   cout << "Could not open movie.txt" << endl;
	    return 1;
	}
	
	while (getline(listfile, name)) 
	{   Movie   temp;
	    temp.name = name;
	    list.push_back (temp); 
	}
	sort (list.begin(), list.end(), compare_movies);    //  Sort the movies read
	cout << "The movies (in alphabetical order) are: " << endl;
	for (unsigned i=0; i<list.size(); i++)
	    cout << list[i].name << endl;
	system ("pause");
	return 0;
}

[rezy3312]

@Thomas1965 I never messed with vectors before need to look into it and also is that the only way I put 100 for the amount of movies that the program can read, i am very new to c++, did I do it incorrectly?

[rezy3312]

@AbstractionAnon thanks for the help but, question what does the push_back do on line 35. and for the sort on line 37 i know that it reads the beginning to the end but what about the third item in the sort function what does that read?

[AbstractionAnon]

what does the push_back do

It appends a movie to the vector.
http://www.cplusplus.com/reference/vector/vector/push_back/

what about the third item in the sort function what does that read?

The third argument is a compare function (line 14). Since Movie is a custom type, we have to tell sort how to compare two Movie entries. See the comp argument on the second prototype here:
http://www.cplusplus.com/reference/algorithm/sort/