Store text based columns data into array C++

Question

I’m trying to store data from a text file into an array in order to use it afterwards. The problem is when there is a header for each data, how can skip a line in the middle of the text or to take it separately?

#include <iostream>
#include <fstream>



main() {
    double tab[100][6] = {0};
    int  i =0, j;
   std::string name = "test.txt";
//   std::cout << "Enter filename: ";
//   std::cin >> name;

   std::fstream file;
   std::string word;
   file.open(name.c_str());
   std::getline(file,word); // skip the first line
   while(file >> word) { //take word and print
      std::cout << word << std::endl;
      for(int j=0; j<=5; j++){
      tab[i][j] = stoi(word);
      }
      i++;
   }
   file.close();
   // displaying
   for(int j = 0; j<= 40;j++){
    std::cout << tab[i][0] << "\t" <<  tab[i][1] << "\t" << tab[i][2] << "\t" << tab[i][3] << "\t" << tab[i][4] << "\t" << tab[i][5];
   }
}

test.txt file

18407022  2018-07-05 00:04:02  MHAM  EIDW  42  S1REB  RYR5GW  3726  JNEIE  837B  Datum  RYR  IFR  Undefined  1  1  2018-07-05  00:15:38  2018-07-05  00:22:56  111  extended
0.0  113416.9  479798.5  -0.2  3.6  0.0
4.0  113395.2  479785.0  1.2  9.3  25.5
8.0  113352.2  479758.7  1.2  16.0  75.9
12.0  113284.9  479717.4  0.5  23.6  154.9
16.0  113189.9  479659.1  -0.5  32.2  266.3
20.0  113064.3  479582.1  -0.9  41.7  413.7
24.0  112904.9  479483.9  -0.3  52.1  600.9
18407022  2018-07-05  00:12:14  MHAM  EIDW  42  S1REB  RYR5GW  3726  JNEIE  837B  Datum  RYR  IFR  Undefined  1  1  2018-07-05  00:30:38  2018-07-05  00:42:56  111  extended
0.0  145431.6  480046.3  4533.3  180.4  0.0
4.0  144747.1  480268.2  4493.4  179.5  719.5
8.0  144059.0  480468.7  4452.0  179.0  1436.2
12.0  143368.6  480655.3  4409.8  178.7  2151.4
16.0  142677.0  480835.6  4367.6  178.6  2866.1
20.0  141985.8  481017.2  4326.1  178.8  3580.9
24.0  141295.9  481207.3  4286.1  179.0  4296.4

XCSM · Accepted Answer · 2021-07-14 15:57:34Z

1

You can try marking each header in the text file as comments by putting a # at the beginning of each header.

Now read the text file like this:

#include<sstream>
...

...
std::ifstream file {"test.txt"};
std::string line;
std::istringstream iss;
double tab[100][6];
int i=0, j;
...

while (getline(file, line))
{
  if (!(line[0]=='#'))
  {
    iss.str(line);

    for (j=0; j<6; ++j)
      iss >> tab[i][j];
    
    iss.clear();

    ++i;
  }
}

file.close();

edited Jul 14, 2021 at 15:57

answered Jul 14, 2021 at 14:48

XCSM

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1 Comment

Random Over a year ago

Thanks, i can also do the same with the first number "18407022" if the number is above 10000000 for example.

MiniMik · Accepted Answer · 2021-07-14 14:44:05Z

1

Maybe you have a look in the complete line first, if there is a letter (a-zA-Z)?!

#include <regex>

...
std::regex e("a-zA-Z");

while(file >> word) { //take word and print
  
  if ( std::regex_match ( word, e))
    continue;
...

answered Jul 14, 2021 at 14:44

MiniMik

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