Reading a file and splitting lines into commas then push back into vector.

[Hamidur]

// I want to read from a file and split each line by comma
// after splitting push those words into a vector and then display vector.
// I tried this code below but did not work as I expected. My text file is
// given under the code.
// My expected output is this
// Hamidur
// Rahman
// MAC
// 125
// MAC
// 190
// MAT
// 231
// Thanks advance.

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

int main ( )
{
	string line;

	int i = 0;

	vector < string > v;

	ifstream fin;

	fin.open( ( "file.txt" ) );

	if ( fin.is_open())
	{
		while ( getline ( fin, line ))
		{
			stringstream ss ( line );

			if ( getline ( ss, line, ','))
			{
				v.push_back( line );
			}
		}

		while ( v.size() )
		{
			cout << v [ i ] << "\n";
			i++;
		}
	}
}

// file.txt has those lines
// Hamidur,Rahman
// MAC,125
// MAC,190
// MAT,231

[keskiverto]

did not work as I expected.

Describe what did happen.


Please use code tags when posting code. See http://www.cplusplus.com/articles/jEywvCM9/
You can edit your post.

[Thomas1965]

I see two problems.

if ( getline ( ss, line, ','))
{
  v.push_back( line );
}

You read only the part in front of the comma.

while ( v.size() )
{
  cout << v [ i ] << "\n";
  i++;
}

That's not the proper way to display vector.
while ( v.size() ) will always be true.
Once i is 4 it will cause an out_of_range exception.

[Hamidur]

@Thomas1965
How do I read parts that are after a comma.

@keskiverto
Thanks. I actually did not know that. I changed it.

[Thomas1965]

Read 2 strings:

  string line = "Anna-Maria,Schmidt";
  stringstream ss(line);
  string firstname;
  getline(ss, firstname, ',');
  string lastname;
  getline(ss, lastname);

  cout << "First name = " << firstname << "\n"
       << "Last name = " << lastname; 

Read a string and a number

  string line = "Anna Schmidt,22";
  stringstream ss(line);
  string firstname;
  getline(ss, firstname, ',');
  int age;
  ss >> age;

  cout << "Name = " << firstname << "\n"
       << "Age = " << age; 

[keskiverto]

I have to disagree with Thomas about the "first problem" -- it is not:

#include <iostream>
#include <string>
#include <sstream>

int main ()
{
  std::string line = "foo,bar,gaz";
  std::stringstream ss(line);
  std::string name;
  while ( getline( ss, name, ',') ) {
    std::cout << "# " << name << " #\n";
  }
  return 0;
}

# foo #
# bar #
# gaz #

The getline ( ss, line, ',') reads up to a comma or end-of-stream, whichever comes first. The word after the last comma is a valid read.


The real issue is the way the data is printed from the vector, like Thomas said.

C++11 has a ranged for syntax that is ideal for this purpose.
A traditional loop is okay too, if written correctly.


I did ask you to describe what did happen, because one can usually realize the problem self when trying to tell it to others. That is important part of programming.

[Hamidur]

I finally figure it out.
Thanks everyone for your time.

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

int main ( )
{
	string line;

	int i = 0;

	vector < string > v;

	ifstream fin;

	fin.open ("file.txt");

	if ( fin.is_open ( ))
	{
		while ( getline ( fin, line ))
		{
			stringstream ss ( line );

			while ( getline (ss ,line, ','))
			{
				v.push_back(line);
			}
		}

		while ( true )
		{
			if ( i == v.size())
			{
				break;
			}

			cout << v [ i ] << "\n";
			i++;
		}
	}
}