What is the C++ implementation for this?

Question

1.00/5 (2 votes)

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I have a Windows text file with the following info inside it:

25 05 38 26 53 04
07 45 50 33 19 34
55 25 21 30 09 39
26 11 30 12 13 41
32 23 44 11 50 39
45 30 07 44 55 54
21 10 35 46 48 27
52 41 05 53 11 50
40 38 17 43 10 54
45 27 29 12 39 31
24 42 38 02 18 09
13 43 28 06 53 30
45 47 29 30 53 13
38 45 28 48 47 36
25 34 18 06 07 55

How can I code them to break that info apart into six columns and put each column into their own array?

[array1] [array2] [array3] [array4] [array5] [array6]
   25	    05	     38	      26       53	    04
   07	    45	     50	      33       19	    34
   55	    25	     21	      30       09	    39
   26	    11	     30	      12       13	    41
   32	    23	     44	      11       05	    39
   45	    30	     07	      44       55	    54
   21	    10	     35	      46       48	    27
   52	    41	     05	      53       11	    50
   40	    38	     17	      43       10	    54
   45	    27	     29	      12       39	    31
   24	    42	     38	      02       18	    09
   13	    43	     28	      06       53	    30
   45	    47	     29	      30       53	    13
   38	    45	     28	      48       47	    36
   25	    34	     18	      06       07	    55

What I have tried:

I'm pretty much stumped at this point...

Posted 5-Feb-21 0:57am

kangkongflea

Updated 5-Feb-21 1:47am

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2 solutions

Solution 1

Read the file line by line using the ifstream class. As you read each line into a char array you can use the C library strtok methods to extract each field one by one, convert it to a numeric value if necessary, and add it to the relevant array.

See <fstream> - C++ Reference[^].

Posted 5-Feb-21 1:08am

Richard MacCutchan

Updated 5-Feb-21 1:54am

v4

Comments

Rick York 5-Feb-21 11:31am

That's what I've done a few hundred times in the past. I use fgets but it's essentially the same.

Richard MacCutchan 5-Feb-21 11:45am

I am trying to discipline myself to use the STL classes rather than the old C run-times. But I fell at the second hurdle :( .

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CPallini · Accepted Answer · 2021-02-05T01:47:00

I would use std::vector instead of C-like arrays.
For instance, the following program

C++

#include<iostream>
#include <vector>
#include <sstream>

using  namespace std;

using vint = vector<int>;

int main()
{
  vector < vint > v = { vint{}, vint{}, vint{}, vint{}, vint{}, vint{} };

  string line;
  while ( getline(cin, line) )
  {
    istringstream iss(line);
    for ( auto & x : v )
    {
      int i;
      iss >> i;
      x.push_back(i);
    }
  }

  for (size_t n = 0; n < v.size(); ++n)
  {
    cout << "v[" << n << "] = ";
    for ( auto i : v[n] )
    {
      cout << i << " ";
    }
    cout << "\n";
  }
}

outputs

v[0] = 25 7 55 26 32 45 21 52 40 45 24 13 45 38 25 
v[1] = 5 45 25 11 23 30 10 41 38 27 42 43 47 45 34 
v[2] = 38 50 21 30 44 7 35 5 17 29 38 28 29 28 18 
v[3] = 26 33 30 12 11 44 46 53 43 12 2 6 30 48 6 
v[4] = 53 19 9 13 50 55 48 11 10 39 18 53 53 47 7 
v[5] = 4 34 39 41 39 54 27 50 54 31 9 30 13 36 55

when fed with your input file (provided by standard input redirection).