Suggestion: Add more documentation for reading .csv data into a program, then exporting it back to a .csv file

[kburchfiel]

Hi Vincent,

First, thanks so much for your hard work on this program! I've found it to be a fantastic tool so far, and the RFC 4180 support (and the ability to read only certain columns into memory) is particularly appreciated.

It might be helpful to add more documentation that shows how to read .csv data into memory, then export that data back to a .csv file. For instance, the following script (which is part of a very early version of a game that I'm working on) specifies a struct (Verse_Row) for rows of a a .csv file; uses your library to read each row into a vector of Verse_Row objects; and then converts each of these objects into a vector of strings so that they can be written back to the same .csv file. I'm sure that this approach could be improved on, but perhaps other newcomers to your library will find this kind of example to be useful.

(The CPDB_for_TTTB.csv file is available here.)

#include "csv.hpp" 
#include <iostream>
using namespace csv;

/* Defining a struct that can represent each row
of CPDB_for_TTTB.csv (the .csv file containing all
Bible verses:) */

struct Verse_Row {
    int verse_id;
    std::string ot_nt;
    std::string book;
    int book_num;
    std::string chapter_num; // This is actually a string, since
    // some values are 'P' (for 'prologue').
    int verse_num;
    std::string verse_code;
    std::string verse;
    int characters;
    int typed;
    double best_wpm;
};

int main() {


// Creating a vector that can store all of the Bible verses:

std::vector<Verse_Row> vrv; // vrv is short for 'Verse Row vector.'

/* Reading data:
This code was based largely on 
https://github.com/vincentlaucsb/csv-parser?tab=
readme-ov-file#indexing-by-column-names
and on
page 22 of A Tour of C++, 2nd Edition by Bjarne Stroustrup. */
std::string verses_file_path = "../Files/CPDB_for_TTTB.csv";
CSVReader reader(verses_file_path);
for (auto& row: reader) {
    Verse_Row vr;
    vr.verse_id = row["Verse_ID"].get<int>();
    vr.ot_nt = row["OT_NT"].get<std::string>();
    vr.book = row["Book"].get<std::string>();
    vr.book_num = row["Book_Num"].get<int>();
    vr.chapter_num = row["Chapter_Num"].get<std::string>();
    vr.verse_num = row["Verse_Num"].get<int>();
    vr.verse_code = row["Verse_Code"].get<std::string>();
    vr.verse = row["Verse"].get<std::string>();
    vr.characters = row["Characters"].get<int>();
    vr.typed = row["Typed"].get<int>();
    vr.best_wpm = row["Best_WPM"].get<double>();
    vrv.push_back(vr);
}

std::cout << "Imported Bible .csv file successfully.\n";
std::cout << "Number of verses imported: " << vrv.size() << "\n";

/* Saving the updated copy of our table of verses to a .csv file:*/

/* This section was based on the documentation found at
https://github.com/vincentlaucsb/csv-parser?
tab=readme-ov-file#writing-csv-files
and 
https://vincela.com/csv/classcsv_1_1DelimWriter.html .*/


std::ofstream verse_output_filename {verses_file_path};
auto verses_writer = make_csv_writer(verse_output_filename);

    // Writing header row to .csv file:
    // It's crucial that the order of these rows matches the order
    // of the corresponding field entries within cols_as_strings.
    std::vector<std::string> header_row = {
    "Verse_ID",
    "OT_NT",
    "Book",
    "Book_Num",
    "Chapter_Num",
    "Verse_Num",
    "Verse_Code",
    "Verse",
    "Characters",
    "Typed",
    "Best_WPM"};

    // Writing this header to the .csv file:
    verses_writer << header_row;
    
    // Converting the fields within each row into a vector
    // of strings:
    // See 
    // https://stackoverflow.com/a/23855901/13097194
    // (which actualy recommends a potentially better solution
    // outside of the stanard library) for to_string().
    for (int i=0; i < vrv.size(); ++i) {
    std::vector<std::string> cols_as_strings = {
    std::to_string(vrv[i].verse_id),
    vrv[i].ot_nt,
    vrv[i].book,
    std::to_string(vrv[i].book_num),
    vrv[i].chapter_num,
    std::to_string(vrv[i].verse_num),
    vrv[i].verse_code,
    vrv[i].verse,
    std::to_string(vrv[i].characters),
    std::to_string(vrv[i].typed),
    std::to_string(vrv[i].best_wpm)
    };
    verses_writer << cols_as_strings;
    };

std::cout << "Finished running program.";

}