问题描述
我正在使用Murach的C ++编程自学C ++。
我在第9章中，如何使用结构和枚举
我正在写电影标题，年份和星星，以表示对电影的看法。
文件通常如下所示：
Casablanca 1942 5
The Wizard of Oz 1932 5
Star Wars 1979 4
Nightmare on Elm Street 2005 4
Home Alone 1990 5
Home Alone 2 1992 4
Home Alone 1990 4
Home Alone 2 Lost In New York 1992 4
Home Alone 3 1997 3
Home Alone 4 - Taking Back The House 2002 2
Home Alone 5 -- The Holiday Heist 2012 2
Star Wars 1977 4
lone Wars 2008 3
Rogue 1: A Star Wars Story 2016 4
Star Wars Holiday Special 1978 3
The Ewok Adventure 1984 2
Ewoks: The Battle For Endor 1985 3
文件视图如下：
NUMBER TITLE YEAR STARS
1 4022333968tCasablanca 1942 5
2 4022333968tThe Wizard of Oz 1932 5
3 4022333968tNightmare on Elm Street 2005 4
4 4022333968tHome Alone 1990 5
5 4022333968tHome Alone 2 1992 4
6 4022333968tHome Alone 1990 4
7 4022333968tHome Alone 2 Lost In New York 1992 4
8 4022333968tHome Alone 3 1997 3
9 4022333968tHome Alone 4 - Taking Back The House 2002 2
10 4022333968ttHome Alone 5 -- The Holiday Heist 2012 2
11 4022334496tStar Wars 1977 4
12 4022334496tClone Wars 2008 3
13 4022334496tRogue 1: A Star Wars Story 2016 4
14 4022334496txStar Wars Holiday Special 1978 3
15 4022334496tThe Ewok Adventure 1984 2
16 4022334496tEwoks: The Battle For Endor 1985 3
4022333968tCasablanca 1942 5
4022333968tThe Wizard of Oz 1932 5
4022333968tNightmare on Elm Street 2005 4
4022333968tHome Alone 1990 5
4022333968tHome Alone 2 1992 4
4022333968tHome Alone 1990 4
4022333968tHome Alone 2 Lost In New York 1992 4
4022333968tHome Alone 3 1997 3
4022333968tHome Alone 4 - Taking Back The House 2002 2
4022333968ttHome Alone 5 -- The Holiday Heist 2012 2
4022334496tStar Wars 1977 4
4022334496tClone Wars 2008 3
4022334496tRogue 1: A Star Wars Story 2016 4
4022334496txStar Wars Holiday Special 1978 3
4022334496tThe Ewok Adventure 1984 2
4022334496tEwoks: The Battle For Endor 1985 3
完整代码如下。
我对代码进行了一些更改，在显示菜单中添加了返回内容，并在视图文件代码中添加了超时时间。
#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <string>
#include <vector>
#include <limits>
////////STriuvctires////////
struct Movie {
unsigned int number;
std::string title = " ";
unsigned int year = 0;
unsigned int stars = 0;
bool equals(Movie&);
};
// member function declaration
// member function deFinition
bool Movie::equals(Movie& to_compare) {
return (title == to_compare.title && year == to_compare.year);
}
const std::string movies_file = "movies.txt";
void display_menu() {
std::cout << "COMMANDS\n"
<< "v - View Movie List\n"
<< "a - Add a movie\n"
<< "d - Delete a movie\n"
<< "x - Exit\n\n";
}
std::vector<Movie> read_movies_from_file (){
std::vector<Movie> movies;
std::ifstream input_file(movies_file);
//Check that file is open
if(input_file) {
Movie movie; // declare a copy of the Movie structure
// to work with
std::string line; // string to hold movie @R_105_4045@ion.
while( getline(input_file,line)) {
std::stringstream ss(line);
getline(ss,movie.title,'\t'); //Get the movie title
ss >> movie.year >> movie.stars; // get year and stars
movies.push_back(movie);
}
input_file.close();
}
return movies;
}
void write_movies_to_file(const std::vector<Movie>& movies){
std::ofstream output_file(movies_file);
if (output_file) { // The file opened successfully
for (Movie movie:movies) {
output_file << movie.number << 't'
<< movie.title << '\t'
<< movie.year << '\t'
<< movie.stars << '\n';
}
output_file.close();
}
}
void view_movies(const std::vector<Movie>& movies) {
int col_width = 8;
std::cout <<std::left
<< std::setw(col_width/2) << " "
<< std::setw(col_width + 2) << "NUMBER"
<< std::setw(col_width * 6) << "TITLE"
<< std::setw(col_width) << "YEAR"
<< std::setw(col_width) << "STARS" << std::endl;
//------------------------------------//
int number = 1;
// loop trough the file line by line
for( Movie movie : movies){
std::cout << std::left
<< std::setw(col_width/2) << " "
<< std::setw(col_width + 2) << number
<< std::setw(col_width * 6) << movie.title
<< std::setw(col_width) << movie.year
<< std::setw(col_width) << movie.stars << std::endl;
++number; // increase the count
}
std::cout << std::endl;
//Code I added to hold the file view until the username
// is ready to move on.
char exit = 'x';
std::cout << "\nPress \'x\' to continue: ";
std::cin >> exit;
while (exit != 'x') {
std::cout << "\nPlease press \'x\' to return to the Menu display: ";
std::cin >> exit;
}
std::cout << std::endl << std::endl << std::endl;
display_menu();
}
Movie get_movie(){
Movie movie;
std::cout << "Title: ";
std::cin.ignore(1000,'\n');
getline(std::cin,movie.title);
std::cout << "Year: ";
std::cin >> movie.year;
std::cout << "Stars: (1-5): ";
std::cin >> movie.stars;
return movie;
}
void add_movie(std::vector<Movie>& movies) {
Movie movie = get_movie();
// Check if movie already exists
bool already_exists = false;
for (Movie& m: movies){
if (m.equals(movie)) {
already_exists = true;
m.stars = movie.stars;
break;
}//ends if()
} // ends for()
if (already_exists) {
write_movies_to_file(movies);
std::cout << movie.title << " already exists and was update.\n\n";
}
else {
movies.push_back(movie);
write_movies_to_file(movies);
std::cout << movie.title << " was added.\n\n";
}
display_menu();
}
int get_movie_number(const std::vector<Movie>& movies){
std::cin.ignore(1000,'\n');
int number;
while (true) {
std::cout << "Number: ";
std::cin >> number;
if (number > 0 && number <= movies.size()) {
return number;
}
else {
std::cout << "Invalid movie number. Try again.\n";
}
}
}
*void delete_movie(std::vector<Movie>& movies){
int number = get_movie_number(movies);
int index = number - 1;
Movie movie = movies[index];
movies.erase(movies.begin() + index);
write_movies_to_file(movies);
std::cout << movie.title << " was deleted.\n\n";
//-----------------//
// Return to display menu
display_menu();
}*
我不知道为什么会这样，而且在网上也找不到任何东西。
感谢您的帮助。
解决方法
数字和字母t来自output_file << movie.number << 't'。 movie.number从未初始化，并且包含随机垃圾。