C++ programming

[Stephanie]

I have a input file (.txt). It has a list of books in the format:
catalogue_number, author_last_name,author_first_name, book_title, genre, availabilty
* The catalogue is 4 characters long
It needs to sort the author_last_name from the input file using array and output as an .txt file.
HOW DO I DO THIS???? I'M VERY CONFUSED.

[TheDestroyer]

Very typical girls request...

I'm sorry but no one is gonna do your homework. Start by reading this:

http://www.cplusplus.com/doc/tutorial/files/

And if you need help, we'll be very glad to provide you all the help you need.

[Stephanie]

I already posted what I did so far earlier.

[Stephanie]

#include <iostream>
#include <iterator>
#include <string>
#include <iomanip>
#include <algorithm>
#include <vector>
#include <fstream>
using namespace std;
class SBooks {
private:
string catalogue_number;
string author_first_name;
string author_last_name;
string book_title;
string strGenre;
string strAvail;
public:
friend bool comp(const SBooks& a, const SBooks& b)
{
return a.author_last_name < b.author_last_name ? true : false;
}

friend ostream& operator<<(ostream& os, const SBooks& s)
{
os << setw(6) << s.catalogue_number << setw(15) << s.author_first_name << setw(15) << s.author_last_name << setw(20) << s.book_title << setw(10) << s.strGenre << setw(14) << s.strAvail;
return os;
}
friend istream& operator>>(istream& is, SBooks& s)
{
is >> s.catalogue_number >> s.author_last_name >> s.author_first_name >> s.book_title >> s.strGenre >> s.strAvail;
return is;
}
};

bool comp(const SBooks& a, const SBooks& b);

int main()
{
const string strFile = "input2.txt";
ifstream is(strFile.c_str());
vector<SBooks> vInput;
// This copies SBook objects into a vector from file input.txt
copy(istream_iterator<SBooks>(is), istream_iterator<SBooks>(), back_inserter(vInput));
cout << "Read in records unsorted: \n";
// This prints the read in output to the screen.
copy(vInput.begin(), vInput.end(), ostream_iterator<SBooks>(cout, "\n"));
// This performs the sorting
sort(vInput.begin(), vInput.end(), comp);
// This prints the sorted output to the screen.
cout << "Sorted: \n";
copy(vInput.begin(), vInput.end(), ostream_iterator<SBooks>(cout, "\n"));
return 0;
}

[Stephanie]

I have to sort with arrays rather than vector and input the .txt and output a .txt with the sort.

[Athar]

Use std::sort on the vector (or array) with a custom comparison function that sorts by last name.
See http://www.cplusplus.com/reference/algorithm/sort/

Edit: didn't see the code.
std::sort works on arrays as well.

[Stephanie]

I'm don't get how I can do it with arrays.

[Athar]

There reference page I linked shows how to do that...

[Stephanie]

That is using vectors.

[Athar]

Sorry, you're right. I thought there was an array example, but I guess not.
With an array, you just pass pointers:
std::sort(array,array+length);

[Stephanie]

How do I pass pointers?

[Athar]

You pass a pointer to the first element of the array and one that points to the element past the last one you want to sort.

const int length=3;
int array[length]={3,2,1};
std::sort(array,array+length);

[Stephanie]

What if the length is long?

[Athar]

As in "of type long"? It doesn't matter.

[Stephanie]

So, in int array length={3,2,1}, my array is of characters so can I leave it blank?

[Athar]

You don't have to explictly specify a size for the array, you just have to pass a pointer to the array end to std::sort (you can use sizeof to figure out the array size).

[Stephanie]

#include <iostream>
#include <iterator>
#include <string>
#include <iomanip>
#include <algorithm>
#include <fstream>
using namespace std;

std::sort(array,array+length)

ifstream instream "input.txt"
ofstream outstream "output.txt"

class Books {
private:
string catalogue_number;
string author_first_name;
string author_last_name;
string book_title;
string strGenre;
string strAvail;

public:
friend bool comp(const Books& a, const Books& b)
{
return a.author_last_name < b.author_last_name ? true : false;
}

friend outstream& operator<<(outstream& os, const Books& s)
{
outstream << setw(6) << s.catalogue_number << setw(15) << s.author_first_name << setw(15) << s.author_last_name << setw(20) << s.book_title << setw(10) << s.strGenre << setw(14) << s.strAvail;
return outstream;
}
friend instream& operator>>(instream& is, Books& s)
{
instream >> s.catalogue_number >> s.author_last_name >> s.author_first_name >> s.book_title >> s.strGenre >> s.strAvail;
return instream;
}
};

bool comp(const Books& a, const Sooks& b);

int main()
{
const string strFile = "input.txt";
intream is(strFile.c_str());
or i=0->sizeof.array - 2 {
for j=i+1->sizeof.array - 1 {
if last_name (i) < last_name (j) {
temp = array (i); array (i) = array (j); array (j) = temp}}}
return 0;
}

[Stephanie]

Would this work?

[Athar]

Okay, now you're just trolling.

[BHX]

Okay, now you're just trolling.

Yep. Think it is safe to say that, or they are just really slow.