File I/O, integers in the file name

I want to read a file, change the data and create say 50 new files from the original file, all numbereder 1 to 50.

So let's say that the original file is called "file.txt" then I want the others to be named "file1.txt" to "file50.txt". The number will be int x and I will have a loop until x > 50. The number may change.

How do I do this? I figured out how to use a string variable as a filename. I tried to see how I can create a new string out of a string and a integer but I can't figure out how to do that.

Oh, I am currently using iostream.

Thanks.

To create new string from the other - use stringstream

Code:

---

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

int main(int argc,char  *argv[])
{
        std::string text("test");
        std::stringstream buffer;
        buffer << text << 5 <<".txt";
        text  = buffer.str();
        std::cout << text;

        return 0;
}

---

Code:

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

using namespace std;


int main ()
{
        ostringstream out;
       
        string str = "file";
        int num = 1;
       
        out<<str<<num<<".txt";

        cout<<out.str()<<endl;

        return 0;
}

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vart's code added the filenames together. Each time through the loop the name of the file became longer. First file is called "offspring1.txt", the second "offspring1.txtoffspring2.txt" etc.


Now maybe I am stupid but I couldn't figure out a way to clear the string each time through the loop. So I switched to 7stud. That gave an error. So I added a buffer like vart's code has:

Code:

---

string offspring_file_name;
ostringstream buffer;
   
buffer<<"offspring"<<z<<".txt";
   
offspring_file_name = buffer.str();
   
   
offspring_file.open (offspring_file_name.c_str());

---

This seems to work.

Quote:

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Originally Posted by Prometheus

vart's code added the filenames together. Each time through the loop the name of the file became longer. First file is called "offspring1.txt", the second "offspring1.txtoffspring2.txt" etc.


Now maybe I am stupid but I couldn't figure out a way to clear the string each time through the loop.

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Sure not my code - my code has no loops.

move stringstream declarartion into the loop. This will construct/destruct variable on each iteration effectively clearing it

Quote:

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Now maybe I am stupid but I couldn't figure out a way to clear the string each time through the loop

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Code:

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string str = "hello";

cout<<str<<endl;
str = "";
cout<<str<<endl;

---

Code:

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ostringstream out;

out<<"hello world "<<3;
cout<<out.str()<<endl;

out.str("");
cout<<out.str()<<endl;

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Note: the str() method can be used to get and set the value of the stringstream.