Question

exampleInput.txt

1 2 3

0 2 3 4

0 1 3 5

0 1 2 6

1 5 6 8

2 4 6 7

3 4 5 9 10

5 8 9

4 7 9

6 7 8

6

How can I detect when 'cin' starts reading from a new line. The amount of numbers in each row is unknown. I need them in type 'int' to use the data.

Also, it will be executed like so, "./a.out < sampleInput.txt".

Answer 1

Thanks for the question, here is how to count the numbers in each line with command line argument

================================================================

#include<iostream>
#include<fstream>
#include<sstream>
#include<string>
using namespace std;

int main(int argc, char* argv[]){
  
   if(argc!=2){
       cout<<"No command line arguments provided. Program will terminate ...";
       return 1;
   }
  
   ifstream infile(argv[1]);
   if(!infile.is_open() || infile.bad()){
       cout<<"Error: could not open file: "<<argv[1]<<endl;
       cout<<"Program will terminate now ...\n";
       return 1;
   }
   string line;
   int lineNum = 1;
   while(getline(infile,line,'\n')){
       stringstream ss(line);
       cout<<"Line >\""<<line<<lineNum++;
       int numCount = 0;
       int num;
       while(ss>>num){
           numCount++;
       }
       cout<<"\" contains "<<numCount<<" number(s).\n";
      
   }
   infile.close();
  

   return 0;
}
===================================================================