从用分号分隔的文件中读取并存储到数组中

Question

I am completely lost and have been trying for hours to read from a file named "movies.txt" and storing the info from it into arrays, because it has semicolons. Any help? Thanks.

movies.txt:

The Avengers     ; 2012     ;  89    ;   623357910.79
Guardians of the Galaxy    ;   2014    ;  96    ; 333130696.46

Code:

#include <iostream>
#include <string>
#include <fstream>
#include <sstream>

struct Movie {
    std::string name;
    int year;
    int rating;
    double earnings;
};

int main()
{
    const int MAX_SIZE = 100;
    Movie movieList[MAX_SIZE];
    std::string line;
    int i = 0;

    std::ifstream movieFile;
    movieFile.open("movies.txt");

    while (getline(movieFile, line, ';'))
    {
        movieFile >> movieList[i].name >> movieList[i].year >> movieList[i].rating >> movieList[i].earnings;
        i++;
    }

    movieFile.close();

    std::cout << movieList[0].name << " " << movieList[0].year << " " << movieList[0].rating << " " << movieList[0].earnings << std::endl;
    std::cout << movieList[1].name << " " << movieList[1].year << " " << movieList[1].rating << " " << movieList[1].earnings << std::endl;

    return 0;
}

What I want is to have:

movieList[0].name = "The Avengers";
movieList[0].year = 2012;
movieList[0].rating = 89;
movieList[0].earnings = 623357910.79;

movieList[1].name = "Guardians of the Galaxy";
movieList[1].year = 2014;
movieList[1].rating = 96;
movieList[1].earnings = 333130696.46;

Answer 1

I amended your code.

#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
#include <vector>

struct Movie {
    std::string name;
    int year;
    int rating;
    double earnings;
};


std::vector<std::string>
split(const std::string &s, char delim = ',')
{

    std::vector<std::string> elems;

    std::stringstream ss(s);
    std::string item;
    while (std::getline(ss, item, delim))
    {
            elems.push_back(item);
    }
    return elems;
}


int main()
{

    std::vector<Movie> movieList;
    std::string line;


    std::ifstream movieFile;
    movieFile.open("movies.txt");

    while (getline(movieFile, line))
    {
        std::vector<std::string> columns = split(line,';');
        Movie movie;

        movie.name     = columns[0];
        movie.year     = std::stoi(columns[1]);
        movie.rating   = std::stoi(columns[2]);
        movie.earnings = std::stof(columns[3]);

        movieList.push_back(movie);
    }

    movieFile.close();

    for (const Movie & m: movieList) 
    {
        std::cout << m.name << " " << m.year << " " << m.rating << " " << m.earnings << std::endl;
    }


    return 0;
}

Basicly, I added a split function that splits the lines using ';'. Also I use vector to store the movies rather than hard coded array of movies. Much better this way.

PS Second version without vectors

#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
#include <vector>

struct Movie {
    std::string name;
    int year;
    int rating;
    double earnings;
};



void split(const std::string &s, char delim, std::string elems[])
{
    std::stringstream ss(s);
    std::string item;

    int i = 0;

    while (std::getline(ss, item, delim))
    {
            elems[i++] = item;
    }
}


int main()
{

    //std::vector<Movie> movieList;

    const int MAX_SIZE = 100;
    Movie movieList[MAX_SIZE];
    int movieNo = 0;

    std::string line;


    std::ifstream movieFile;
    movieFile.open("/home/marcin/testing/movies.txt");

    std::string columns[4];

    while (getline(movieFile, line))
    {
        split(line,';', columns);

        movieList[movieNo].name     = columns[0];
        movieList[movieNo].year     = std::stoi(columns[1]);
        movieList[movieNo].rating   = std::stoi(columns[2]);
        movieList[movieNo].earnings = std::stof(columns[3]);

        ++movieNo;

    }

    movieFile.close();

    for (int i =0; i < movieNo; ++i) {
        std::cout << movieList[i].name
                  << " "
                  << movieList[i].year
                  << " "
                  << movieList[i].rating
                  << " "
                  << movieList[i].earnings
                  << std::endl;
    }


    return 0;
}

Answer 2

Use getline(my_movieFile, movie_name, ';') to get the name of the movie up to the ;.

You'll need to figure out how to remove the trailing whitespace from the name if necessary.. you can search for examples.

Read the rest of the line using getline(movieFile, line)

Use std::replace to replace all ; with a space in line

Put line into a std::stringstream .

Then extract the remaining fields from the stringstream using the >> operators.

Put this in loop do { ... } while (movieFile);

Also, don't hardcode an arbitrary number of movies. Use a std::vector<Movie> and push_back to add new ones.

Answer 3

I think you want to break your line into tokens using something like std::strtok . Check out the reference here . The example given on that page uses a blank as a separator, you would use a semicolon.