String concatenation

[ndpndp]

Hi i am new to programming and trying to write a simple program which is able to read the txt file line by line and append e3 at the end of each line. Can anyone help me in this pgm?

[MrHutch]

Can you post your current progress?

[ndpndp]

#include <string>
#include <fstream>
#include <vector>

using namespace std;

int main()
{
  vector<string> text_file;

  ifstream ifs( "data.txt" );
  string temp;
  for (int i=0; i<temp; i++)
  			file << temp << "e3 "<<endl;

  while( getline( ifs, temp ) )
     text_file.push_back( temp );
}

[MrHutch]

You're using the string class, so you can concatenate using the += operation.

Example,

#include <fstream>
#include <string>
#include <vector>
#include <iostream>

int main()
{
   ifstream in_file("data.txt");
   string temp;
   vector <string> str_list;

   if (in_file.is_open())
   {
      while (in_file.good())
      {
         getline(in_file, temp);   // Assign line to temp
         temp += "e3";             // String concatenation
         str_list.push_back(temp); // Push string to vector
      }
   }
   else
      cout << "Unable to open file\n";

   return 0;
}

Hope this helps.

[ndpndp]

Thanks for the help, but the program is terminating without and errors or warning. Nothing has changed in my txt file

[MrHutch]

Oh, sorry. I misunderstood - you want the appended strings to be put back into a text file.

You can add this before the return. Beware, giving it the same name as your input file will overwrite it. If you want a separate file, give it a different name.

ofstream out_file ("data.txt");

if (out_file.is_open())
{
   for (int i=0; i < str_list.size(); i++)
   {
       out_file << str_list[i] << "\n";
   }
   out_file.close()
}
else
   cout << "Couldn't open output file\n";

[ndpndp]

Thanks it was able to do the job :)