stringstream getline() only reading first line of cells

[wolfv]

I want the following code to print all the cells of a comma separated values (csv) file.
It only prints the first row of cells.
Why is it not printing cells of the remaining rows?

Thank you.

code:

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

class CSVMatrix
{
    public:
        void loadMatrix(std::istream& inStream)
        {
            std::string         line;
            std::stringstream   lineStream;
            std::string         cell;

            int row=0;

            //read lines
            while( std::getline(inStream, line) )
            {
                std::cout << "row=" << row++ << " line=" << line << std::endl;
                lineStream << line;

                //read cells
                while(std::getline(lineStream, cell, ','))
                {
                    std::cout << "cell=" << cell << std::endl;
                }
            }
        }
};

int main()
{
    std::ifstream       infile("plop.csv");
    CSVMatrix           matrix;

    matrix.loadMatrix(infile);
}

input file plop.csv:

1,2,3,4,5,
a,b,c,d,e
m,n,o,p,q,
u,v,wz, x ,y,

output:

row=0 line=1,2,3,4,5,
cell=1
cell=2
cell=3
cell=4
cell=5
row=1 line=a,b,c,d,e
row=2 line=m,n,o,p,q,
row=3 line=u,v,wz, x ,y,

[Chervil]

After the while loop at line 24 has completed, the lineStream will have a fail status.
Before the next use of that stream, reset the flags:

lineStream.clear();

Also, it may not matter much here, but the size of that stringstream is gradually increasing,
try

    std::cout << "lineStream.str() = " << lineStream.str() << '\n';

to see the contents.

To make it contain just the current line, you could use

    lineStream.str(line);

instead of

    lineStream << line;

[LukeShen]

because the error flag of lineStream is set after the first line.

try replace lineStream << line
with

lineString.clear();
lineString.str() = line;

[integralfx]

Alternatively, check for eof() and exit the loop if true.

while( std::getline( lineStream, cell, ',' ) ) {
    if( lineStream.eof( ) ) break;

    std::cout << "cell=" << cell << '\n';
}

[Chervil]

Alternatively, check for eof() and exit the loop if true.

As an alternative to what?

[wolfv]

Thank you folks, that worked great:

#include <iterator>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>

class CSVMatrix
{
    public:
        void loadMatrix(std::istream& inStream)
        {
            std::string         line;
            std::stringstream   lineStream;
            std::string         cell;

            int row=0;

            //read lines
            while( std::getline(inStream, line) )
            {
                lineStream.clear();
                lineStream.str(line);
                std::cout << "row=" << row++
                    << " lineStream.str() = " << lineStream.str() << std::endl;

                //read cells
                while(std::getline(lineStream, cell, ','))
                {
                    std::cout << "cell=" << cell << std::endl;
                }
            }
        }
};

int main()
{
    std::ifstream       infile("plop.csv");
    CSVMatrix           matrix;

    matrix.loadMatrix(infile);
}

output:

row=0 lineStream.str() = 1,2,3,4,5,
cell=1
cell=2
cell=3
cell=4
cell=5
row=1 lineStream.str() = a,b,c,d,e
cell=a
cell=b
cell=c
cell=d
cell=e
row=2 lineStream.str() = m,n,o,p,q,
cell=m
cell=n
cell=o
cell=p
cell=q
row=3 lineStream.str() = u,v,wz, x ,y,
cell=u
cell=v
cell=wz
cell= x 
cell=y