/** * Author: Xan * Date: 20th April 2018 * * Answer to question: * https://www.sololearn.com/Discuss/1224795/how-can-i-sort-char-line-according-to-alphabet-order-i-have-a-problem-with-in-below-code-with-it * * Note: This won't run in the Code Playground on SoloLearn * because it requires the loading of a file, which SoloLearn can't handle. */ /** * This is the next improved version: * https://code.sololearn.com/cpVyM8aCxbuK/#cpp * * This new version avoids loading the whole file into memory first... * instead it only keeps a list of the books with the publishing year * we are searching for. */ #include #include #include #include #include #include #include using namespace std; class Book { public: int regnum; string author; string title; int year; string printname; int pages; public: // The sort method (we want to search by title). bool operator<(const Book &a) const { return (title < a.title); } }; // Define the search method (we want to search by year). struct BookSearchByYear: public binary_function { bool operator() (const Book &book, const int &year) const { return book.year == year; } }; int main() { list booksList; Book loadedBook; ifstream ifs; // Try to open the book data file. try { ifs.open("Booksinfo.txt"); } catch (int e) { // Note we can't assume failure just means the file doesn't exist. // It could fail for various reasons, so give a more accurate error message. cout << endl << "ERROR: Failed to open file!" << endl << endl; exit(1); } // While we still have information to read from the books file, do... while (!ifs.eof()) { // Load a book. ifs >> loadedBook.regnum; ifs >> loadedBook.author; ifs >> loadedBook.title; ifs >> loadedBook.year; ifs >> loadedBook.printname; ifs >> loadedBook.pages; // Push this book into the books list // (we keep a copy for working on later). booksList.push_back(loadedBook); } // Get the year the user wants to search by. int year; cout << "Give published year: "; cin >> year; // Sort the books by title. booksList.sort(); // No books found so far. int num_books_found = 0; list::iterator result = booksList.begin(); bool still_searching = true; while (still_searching) { // Search for a book, that has the published date 'year'. result = find_if(result, booksList.end(), bind2nd(BookSearchByYear(), year)); // If we got to the end, without any results, then... if (result == booksList.end()) { // Quit searching. still_searching = false; } else { // One more book found. num_books_found++; // Output the book details. cout << setw(4) << num_books_found << ": " << result->regnum << ", " << result->author << ", " << result->title << ", " << result->year << ", " << result->printname << ", " << result->pages << endl; // Go onto the next result. result++; } } // If no books are found then tell the user. if (num_books_found == 0) { cout << endl << "No books found with that search criteria." << endl << endl; } return 0; // The person wanting help, asked // for this: // // This code outputs info about books which are published given particular year, // and it takes info from file "Booksinfo". // How can I sort in_year[].title array, according to the alphabet order? }

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