Question

Write a C++ program that creates a ragged table (i.e. a table with rows of different length) using a vector of vector of integers. Your program should prompt the user for a file name, open the file, read the content of the file and store it in a vector or vectors, and finally print the content of the vector of vectors.

Sample Input:

Enter the file name: data.dat

A sample file might contain:

6
5 2 4 5 3 2
3 1 2 6
0
4 9 3 1 7
1 5
2 3 6

The first number in the file is a whole integer (i.e. 0, 1, 2, …) representing the number of rows of values on the remaining lines in the file. For example, the first 6 in the example shown above indicates there are 6 lines of numbers after the first line. Each row of data (second line in the sample shown above) begins with a whole number representing the number of items on the line. For example, first row of data begins with a 5 indicating there are 5 data values on the line (i.e. 2 4 5 3 2). After you have read and stored the values in a vector of vectors, write a pair of nested loops to print the vector of vectors.

When you print the vector of vector for the example given above you should display:

2 4 5 3 2
1 2 6

9 3 1 7
5
3 6

Notice a zero length row is displayed as a blank line (i.e. endl)

Make sure your solution can handle a file containing the following:

3
0
0
0

as well as a file containing:

0

Answer 1

Given below is the code for the question. Please do rate the answer if it helped. Thank you.
data.dat
----
6
5 2 4 5 3 2
3 1 2 6
0
4 9 3 1 7
1 5
2 3 6

main.cpp
-----
#include <vector>
#include <fstream>
#include <iostream>
using namespace std;
int main(){
   string filename;
   vector< vector <int> > table;
   int numRows, numValues, num;
  

   cout << "Enter the file name: ";
   cin >> filename;
  
   ifstream infile(filename.c_str());
   if(infile.fail()){
       cout << "ERROR: could not read input file " << filename << endl;
       return 0;
   }
  
   infile >> numRows;
   for(int i = 1; i <= numRows; i++){
       vector<int> v;
       infile >> numValues;
       for(int j = 1; j <= numValues; j++){
           infile >> num;
           v.push_back(num);
       }
       table.push_back(v);
   }
  
   infile.close();
  
   //print the data
   for(int i = 0; i < table.size(); i++){
       for(int j = 0; j < table[i].size(); j++)
           cout << table[i][j] << " ";
       cout << endl;
   }
   return 0;
}