CSV

It is a C++ library that allows reading and writing to CSV files. It was designed with efficiency and simplicity in mind. The library gives the programmer freedom, for example, in choosing a data structure for storing input/output data. It has also been well tested.

Reading

Reading is enabled using the csv::reader class. It takes the number of columns of the CSV file and a parser as its class template parameters. The default parser is csv::parser, which allows conversion of std::string_view to numbers, enums, and std::string. A custom parser can also be provided.

The read_header method allows reading header into an instance of std::array. Returns a boolean indicating whether it read the header. Returns false if the file is empty.

The read_row method is used to read a row of the CSV file directly into the variables provided using the template parameter pack. It returns true if the line has been read, false otherwise, so it can be used in a while loop to read the entire file. Throws an std::runtime_error if the file is malformed: the values cannot be parsed or the specified number of columns is greater than the actual number stored in the file.

The use of the class can be seen in the example below:

struct person {
    std::string name;
    int age;
};

constexpr std::size_t n_cols = 2;
csv::reader<n_cols> reader{{"dir/people.csv"}};

std::array<std::string, n_cols> header;
std::vector<person> people;
person p;

reader.read_header(header);
while (reader.read_row(p.name, p.age))
    people.emplace_back(p); 

Writing

Writing is enabled using the csv::writer class. It takes the number of columns of the CSV file and a stringifier as its class template parameters. The default stringifier is csv::stringifier, which allows conversion of numbers and enums into std::string. A custom stringifier can also be provided.

The write_header method allows writing a header and takes an instance of std::array as an argument. The write_row method is used to write the values passed to it directly into rows. Both methods do not throw any exceptions.

The use of the class can be seen in the example below:

struct person {
    std::string name;
    int age;
};

constexpr std::size_t n_cols = 2;
csv::writer<n_cols> writer{{"dir/people.csv"}};

std::array<std::string, n_cols> header{"Name", "Age"};
std::vector<person> people{
        {"Jane",   21},
        {"Max",    47},
        {"George", 7}
};

writer.write_header(header);
for (const auto& p: people)
    writer.write_row(p.name, p.age);