file_reader.hpp

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#ifndef FILE_READER_HPP
#define FILE_READER_HPP

#include <fstream>
#include <iostream>

class FileReader{

    std::ifstream ifile;
    std::string filename;

    public:

    void open(const std::string& input){
        // Open file
        ifile = std::ifstream(input, std::ios::in);

        // Check to see that the file was opened correctly:
        if (!ifile.is_open()) {
            std::cerr << "There was a problem opening the input file '" << input << "'.\n";
            exit(1); // exit or do additional error checking
        }

        filename = input;
    }

    // Read an array from plain text file
    template<typename T>
    void read(T* var, int n){
        int i = 0;
        T num = 0;
        // Store values from text file to array
        while (i<n && ifile >> num) {
            var[i] = num;
            i++;
        }

        // If there was insufficient data in the file to fill the array
        if (i!=n){
            std::cerr << "Error parsing file '" << filename << "': Reached end of file, but more data was expected!\n";
            exit(1);
        }
    }

    // Skip some data
    void skip(int n){
        int i = 0;
        int num = 0;

        // Read data but ignore it
        while (i<n && ifile >> num) {
            i++;
        }

        // If there was insufficient data to skip n values
        if (i!=n){
            std::cerr << "Error parsing file '" << filename << "': Reached end of file, but more data was expected!\n";
            exit(1);
        }
    }

    // Skip entire line
    void skip_line(){
        std::string line;
        getline(ifile, line);
    }

    // Skip multiple lines
    void skip_lines(int n){
        for(int i=0; i<n; i++){
            skip_line();
        }
    }
};

#endif