c++ - 如何将文件中的数据导入我的结构数组？

Question

这是我的结构:

struct Event{
    int day;
    int month;
    int year;
    int weekday;
    string event;
};

我的事件数据文件应该是这样的:

# Comment and empty lines are ignored
# ’$’ means LAST, ’*’ is wildcard
# Weekday on symbolic from Mon,Tue,Wed,Thu,Fri,Sat,Sun
# Events specs start
# Last day is payday
$.*.*:*:Payday
# Birthday at 1.3
1.3.*:*:Birthday Party
# Darts on Fridays
*.*.*:Fri:Darts evening
13.*.*:Fri:Friday the 13th
# EOF

我试着写了这个函数:

void readFile(vector<string> &data){
    string line;
    ifstream readFile("events.dat", ios::in);
    if (!readFile) {
        cerr<<"File COuld not be opened"<<endl;
        exit(EXIT_FAILURE);
    }
    while (readFile && !readFile.eof()) {
            getline(readFile,line);
            if (line.length() == 0 or line[0] == '#' or line[0] == '/')
                break;
            data.push_back(line);
        }
    }

但现在我不知道如何将数据 vector 转换为事件 vector ？

Answer 1

你可以用 std::istringstream 和 std::getline 来完成，它有第三个参数是一个 char它应该停止消耗字符并返回字符串。另一种方法是使用正则表达式，下面是一种使用正则表达式解析它的方法，我只用一个字符串对其进行了测试，但它应该让你开始如何去做。

http://coliru.stacked-crooked.com/a/d3aed577b2f72bd7

#include <iostream>
#include <string>
#include <regex>

struct Event{
    int day;
    int month;
    int year;
    int weekday;
    std::string event;
};

int main()
{
    std::regex pattern("([0-9\\$\\*]+)\\.([0-9\\$\\*]+)\\.([0-9\\$\\*]+):(\\w+):([\\w ]+)" );
    std::string line = "13.*.*:Fri:Friday the 13th";
    std::smatch sm;
    Event evt;
    if (std::regex_match(line, sm, pattern)) {
        std::string val1 = sm[1];
        if (val1 == "*")
            evt.day = -1; // wildcard
        else if (val1 == "$")
            evt.day = -2; // last
        else 
            evt.day = std::stoi(val1);

        val1 = sm[2];
        if (val1 == "*")
            evt.month = -1; // wildcard
        else if (val1 == "$")
            evt.month = -2; // last
        else 
            evt.month = std::stoi(val1);

        val1 = sm[3];
        if (val1 == "*")
            evt.year = -1; // wildcard
        else if (val1 == "$")
            evt.year = -2; // last
        else 
            evt.year = std::stoi(val1);


        std::string weekDay = sm[4];
        std::vector<std::string> weekdays = {"Mon", "Tue", "Wen", "Thr", "Fri", "Sat", "Sun"};
        auto it = std::find(weekdays.begin(), weekdays.end(), weekDay);
        evt.weekday = std::distance(weekdays.begin(), it);

        evt.event = sm[5];

        std::cout << evt.day << ", " << evt.month << ", " << evt.year << ", " << evt.weekday << ", " << evt.event << "\n";      
    }
}

关于输出:

 13, -1, -1, 4, Friday the 13th