c++ fast-cpp-csv-parser into array

Question

found this lib for csv parsing https://github.com/ben-strasser/fast-cpp-csv-parser and I am trying to get the data into 2d array. I have a problem with useability as the lib is constructed in a specific manner

 bool read_row(ColType1&col1, ColType2&col2, ...);

Going from example presented in github, I came up with:

main() {

double** data = new double*[5];
for (int i = 0; i < 4; ++i) {
    data[i] = new double[5];
}

io::CSVReader<5> in("c:/code/test.txt");
//in.read_header(io::ignore_extra_column, "vendor", "size", "speed");
double a; double b; double c; double d; double e;
int n = 0;
while (in.read_row(a, b, c, d, e)) {
    printf("time elapse: %f\n", c); 

    data[n][0] = a;
    data[n][1] = b;
    data[n][2] = c;
    data[n][3] = d;
    data[n][4] = e;

    n++;

}


for (int i = 0; i < 4; i++){ 
    for (int j = 0; j < 5; j++) {
        printf("data %f\n", data[i][j]);
    }
}

}

This does the job, goes through 4 lines with 5 columns and as to example I had to present a variable for every column. How to modify the code to take thousands of columns? Is there a better/easier way to process csv into 2d array? My goal is speed, I know exact formating of csv input, num of lines and columns, so no checks needed.

John Zwinck · Accepted Answer · 2017-12-02 12:51:19Z

1

You say your input CSV files have thousands of columns. The library you have linked does not effectively support such a use case (after all, almost no one has thousand-column CSV files).

A simple and still fast method will be to read one line at a time (std::getline() or fgets()), then split by commas explicitly.

answered Dec 2, 2017 at 12:51

John Zwinck

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