Thread: Error, std::stringstream no member 'c_str'

I fixed some errors and compiled this code in vs 2010 express c++;

Code:

#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <fstream>
#include <cstdlib>
using namespace std;
 
class Base{
 public:
 int iDbugPrtCt;
 string ReVestFileName;
 ofstream DrawDn_File;
 ofstream ReVest_File;
 
 Base();
 ~Base();
 
 void Output();
 int Re_InVestCalc();
};  // End of Base Class declaration
 
// Base Ctor
Base::Base()
{  iDbugPrtCt = 0;  }
 
// Base Dtor
Base::~Base()
 { /*nothing yet*/  }
 
void Base::Output()
{
  DrawDn_File.open("DrawDown.txt");
 
  if (!DrawDn_File.good())
  { cerr << "Problem opening DrawDown file"; exit(1);
  }
 
  iDbugPrtCt++ ;
  DrawDn_File << "Entered Output Func, output # " << iDbugPrtCt << "\n";
 
  if (DrawDn_File.fail() )
  { cerr << "Failed write DrawDown file"; exit(1);
  }
 
  Re_InVestCalc();
 
  iDbugPrtCt++ ;
  DrawDn_File << "Back from Re_InVestCalc, output # " << iDbugPrtCt << "\n";
 
  if (DrawDn_File.fail() )
  { cerr << "Failed write DrawDown file"; exit(1); }
 
} // End of Base::Output Func
 
int Base::Re_InVestCalc()
{ /* what I want is to insert a numerical counter in the filename 
     since later I will create a new file for each iteration. As you
     see I've having trouble getting it into a const char ptr that 
     ofstream appears to require
  */
  stringstream sItoS;
  sItoS << iDbugPrtCt;   // int to string,
  string sFilename2 = "ReInvest_" ;
  sItoS << ".txt" ;
  sFilename2 = sItoS.str();  //<-Draws error
          // Error, std::stringstream has no member named 'c_str'
 
  ReVestFileName = sFilename2;
 
  ReVest_File.open("ReInvest.txt",  ios_base::out | ios_base::app );
 
  if (!ReVest_File.good())
   { cerr << "Problem opening Re-invest file"; exit(1); }
   
 
  iDbugPrtCt = iDbugPrtCt + 1 ;
  ReVest_File << "Inside Re_InVestCalc, output # " << iDbugPrtCt << "\n";
 
  ReVest_File << "sFilename is " << sFilename2  << "\n";
 
  return 0;
 }  //End of Base::Re_InVestCalc Func
 
int main()
{
  Base ObjRun;
  ObjRun.Output();
 
  //std::cin.get(); // Only for viewing output in real time.
  return 0;
}

I hope that helped you.

Ok, sorry, not sure where I foo barred in my google, but it's academic now.

Thanks to your help though I kept prodding on with how to accomplish building the filename at run time and then get it back to a const char to pass to ofstream. I came up with two options below.

Now my question is there a better way to do this than either of what I have here ?

Code:

stringstream sItoS;
string sStringName, sStringCt;
sItoS << iDbugPrtCt;   // int to stringstream
sItoS >> sStringCt;    // stringstream to string
sStringName = "Reinvest" + sStringCt + ".txt"; // build string
ReVestFileName = sStringName.c_str();   // now I use c_str() to get back to const char*
const string& sAlternate = "Reinvest" + sStringCt + ".txt"; // But apparently could have used this
                                                            // to pass to ofstream.open also

//ReVest_File.open( ReVestFileName,  ios_base::out | ios_base::app ); // this or the below both 
ReVest_File.open( sAlternate,  ios_base::out | ios_base::app );       // seem to work.

Originally Posted by whiteflags

Not really, although I suppose you could cut down on the number of variables. stringstream lets you build strings, so you may as well take full advantage of that.

Code:

stringstream ReVestFileName;
ReVestFileName << "Reinvest" << iDbugPrtCt << ".txt";
ReVest_File.open(ReVestFileName.str(), ofstream::app); // ReVestFileName.str().c_str() is also fine

The file name can be reset at any time by calling ReVestFileName.str("");

I think the totally object oriented approach is a bit hasty, too, but that is a subject for another time.

Well yea there really was no reason to write a full blown class for this, just wanted to. I had programmed to a hobby novice level about 6 yrs ago in C++ paradigm, but health issues put me down for a long time. I'm retired and trying to pick it up again just to keep busy. And I like writing stuff for my curiousities. I used to work for a civil engineering company so I have lots of routines I could make use of coding to share with those still working. You guys are kind to give me your time, I'll try not to waste it.

Originally Posted by laserlight

I'd say that whiteflags' suggestion of just using the stringstream to build the string is what stringstreams are for, beyond merely converting from an integer to a string, and it is definitely a better way than what you did.

That said, especially if you are dealing with more variables to be formatted or with more complex formatting, you could consider Boost.Format, which is implemented using stringstreams. In your case, this could simplify the code to:

Code:

ReVest_File.open(str(boost::format("Reinvest_%1%.txt") % iDbugPrtCt), ofstream::app);

Thanks to both you guys, cool, so while I'm banging my way back to c_str(), stringstream.str() returns the same compatible type to ofstream.open all along.

Originally Posted by Elysia

I'll also mention there's std::to_string to convert integers to strings. And VS 2010 is quite old, so strongly consider upgrading.

Thanks I knew about it's type conversion abilities. And the VS2010 (lol) well I'm just a novice on free Dev C, it's ok most of the time, some times I have to reset the attributes on the output file for some reason to get it to compile & Link. I do have a Pro copy of VS 2005 on a CD, but haven't installed it yet.

Hey what font do you guys use in your IDE's ? I like Consolas, it's a fixed width but I hate that it's lower case l is the same as tne number 1.

Thanks to both you guys, cool, so while I'm banging my way back to c_str(), stringstream.str() returns the same compatible type to ofstream.open all along.

fstream::open() is an init method basically. stringstream::str() did not return an instance of ofstream, as you make it sound. Rather, it returned a string, representing the (implicit) path and file name you wanted to open. You see this when you look at open's signature:
ofstream::open - C++ Reference

Code:

void open (const   char* filename,  ios_base::openmode mode = ios_base::out);
void open (const string& filename,  ios_base::openmode mode = ios_base::out);

In normal code you would call one of these.

Originally Posted by whiteflags

fstream:pen() is an init method basically. stringstream::str() did not return an instance of ofstream, as you make it sound. Rather, it returned a string, representing the (implicit) path and file name you wanted to open. You see this when you look at open's signature:
ofstream:pen - C++ Reference

Code:

void open (const   char* filename,  ios_base::openmode mode = ios_base::out);
void open (const string& filename,  ios_base::openmode mode = ios_base::out);

In normal code you would call one of these.

Thanks again, actually I meant what you said in that it returns "filename" of the required arg type. I didn't mean instance of the object. I guess I just don't speak it right.

Originally Posted by Elysia

Get VS2015 Community. It's free.

Default font.

Thanks but won't the free version require anyone I share my routines with have "whatever" installed for managed code ? I.e. it doesn't produce stand alone native code does it ?

Obviously I'm not writing anything real big, just small stuff to make the jobs I used to do easier for those who still do it.