naming the output file and writing to it

[Flat Four]

Hi all

I am having trouble giving the user the option to name the output file (using Dev-C++) and then writing to that particular output file. Here is my code thus far (note-some of the stuff I have in there is incomplete, I know):

#include<iostream>
 #include<fstream>
 #include<iomanip>
 #include<cmath>
 using namespace std;
 
 const double e=2.71828183;
 const double c1=374200000, c2=14390;
 double E, frac;
 double wave_start, wave_final; 
 double wave_inc, temp;
 double test;
 
 
 void info_block();
 void file_print();
 void file_print_clean();

 int main ()
 {
     cout<<"Please enter a starting value for the wavelength range: ";
     cin>>wave_start;
     cout<<"Please enter an ending value for the wavelength range: ";
     cin>>wave_final;
     cout<<"Please enter a value for the wavelength increment: ";
     cin>>wave_inc;
     cout<<"Please enter a value for temperature in Kelvin: ";
     cin>>temp;
     
     string filename;
     ofstream outfile;
     cout<<"What is the name of the output file? (be sure to include extension)";
     cin>>filename;
     outfile.open(filename.c_str());

    info_block();
    
    for (wave_start; wave_final>=wave_start; wave_start=wave_start+wave_inc)
     {
       frac=(c2/(wave_start*temp));
       E=c1/((pow(wave_start,5))*((pow(e,frac))-1));
       cout<<"\t\t    "<<wave_start<<"\t\t      "<<E<<endl;
       filename.c_str()<<"\t\t    "<<wave_start<<"\t\t      "<<E<<endl;
     }
     
     
     
system("pause");
return(0);
}

void info_block()
{
     cout<<"\n\t\t  Energy report for T = "<<temp<<endl;
     cout<<"\n\t\t Wavelength";
     cout<<"\t\t  E "<<endl;
     cout<<"\t\t ---------- \t\t ---"<<endl;
}

void file_print()
{
 }

And I'm getting my error here:

 filename.c_str()<<"\t\t    "<<wave_start<<"\t\t      "<<E<<endl;

That's where I'm trying to write to the outfile. The error I'm getting is:

invalid operands of types `const char*' and `const char[7]' to binary `operator<<'

What am I doing wrong here? Any help would be appreciated! If I need to go about naming the outfile in a completely different method, just let me know. I am open to any and all help/changes. Thanks!

[Flat Four]

Also, is it possible to create more than one outfile for one program? Basically I need one version with the void info_block() in the outfile and one without it. I need the one without it so I can import it into MATLAB.

[moorecm]

You need to send your output to the ofstream named outfile. Try:
outfile<<"\t\t "<<wave_start<<"\t\t "<<E<<endl;

[Flat Four]

Ah that worked nicely! I was hoping for a simple fix and I got one haha. Now to figure out how to make two outfiles.

[Incubbus]

same as the first one... or use outfile.close() and open it with another filename using outfile.open()...

[Flat Four]

Alright I'll give that a try. Like I said before, I'm trying to print one outfile with the info_block header and one without. As the program stands right now, it's making one outfile without the info_block header. Im fiddling around with it trying to get it to print the info_block header to the outfile, but I cant seem to get it to work. How would I go about this?