[英]Reading from file separated with semicolons and storing into array
我完全迷失了,已經嘗試了幾個小時從一個名為“ movies.txt”的文件中讀取信息,並將其信息存儲到數組中,因為它具有分號。 有什么幫助嗎? 謝謝。
movies.txt:
The Avengers ; 2012 ; 89 ; 623357910.79
Guardians of the Galaxy ; 2014 ; 96 ; 333130696.46
碼:
#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;
}
我想要的是:
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;
我修改了您的代碼。
#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;
}
基本上,我添加了一個split函數,該函數使用';'分隔行。 另外,我使用矢量來存儲電影,而不是硬編碼的電影數組。 這樣好多了。
PS第二版,不含向量
#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;
}
使用getline(my_movieFile, movie_name, ';')
可以獲取電影的名稱,直到;;。
如果需要,您需要弄清楚如何從名稱中刪除尾隨空格。您可以搜索示例。
使用getline(movieFile, line)
讀取其余部分
使用std::replace
替換所有;
line
將line
放入std::stringstream
。
然后使用>>
運算符從字符串流中提取其余字段。
將其放入循環中do { ... } while (movieFile);
另外,請勿硬編碼任意數量的電影。 使用std::vector<Movie>
和push_back
添加新的。
我認為您想使用std::strtok
類的東西將行划分為令牌。 在此處查看參考。 該頁面上給出的示例使用空格作為分隔符,您將使用分號。
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