#include <cstdlib>
#include <fstream>
#include <iostream>
#include <iterator>
#include <list>
#include <string>

using namespace std;

istream& GetLines(istream& is, list<string>& list) {
    string str;
    if (list.size() > 0) {
        list.clear();
    }
    while (getline(is, str, is.widen('\n'))) {
        list.push_back(str);
    }

    return is;
}

void Print(const list<string>& list) {
    for (auto it = list.cbegin(); it != list.cend(); it  ) {
        cout << *it << endl;
    }
}

void SortAndUnique(list<string>& list) {}

int main() {
    list<string> list;
    ifstream f(
        "/home/jacksparrow/Downloads/university/project/module3/Module_3/"
        "T2-list/src  /main.cpp");

    // Read the file into list
    if (!f.is_open() || !GetLines(f, list).eof()) {
        cout << "Opening error: Error reading main.cpp" << endl;
        return EXIT_FAILURE;
    }

    Print(list);
    cout << "---" << endl;

    // Sort and unique
    SortAndUnique(list);
    Print(list);

    cout << "---" << endl;
    // Print again
    Print(list);

    return 0;
}

I have got the above code in a file "main.cpp" and, I read this file "main.cpp" into a list "list list;", now what I want to do is to sort that list into alphabetical order and remove the duplicate strings. Also, this upper code is my main.cpp file in which I included (#include "list.cpp" ) file which's code is written below and does 3 functions:

1. Reads the file data into the list "getline()".
2. Prints the list Print()
3. sort that "list" into alphabetical order and, removes the duplicate strings SortAndUnique().

CodePudding user response：

The proper way to solve this is as suggested to read the documentation about the container you are using and in std::list Operations, you'll find this list:

The linked member functions are overloaded:

std::list::sort:

• void sort();
  

• template< class Compare >
  void sort( Compare comp );
  

std::list::unique:

• size_type unique();
  

• template< class BinaryPredicate >
  size_type unique( BinaryPredicate p );
  

In your case you do not need to provide a Compare functor or a BinaryPredicate since the overloads taking no arguments already do what you want.