How can i create filename using interger with gnu C++?

cash_05 · 09-12-2003, 11:58 AM

Hi,

I'm thinking of writing a c++ program that will automatci generate some files. My desire filename is from file001 to file999. I will like to use a loop to do that. For example,

..................
const string filepre = "file";
string filename;
int i,;
..................
..................
for (i=1; i<1000; i++) {
filename = filepre + i;
ofile.open(filename);
ofile << i;
ofile.close(filename);
}

But, when i try to compile, the compilre always return some type conversion error.

Can anyone help me to resolve me, guiding me the proper way to do this.

Thanks in advance.

acid_kewpie · 09-12-2003, 12:01 PM

try using sprintf()

Strike · 09-12-2003, 12:37 PM

Also, unless this is an exercise in learning C/C++, this can easily be done in a simple shell script:

Code:

for i in `seq -f%03.f 1 999`; do echo i > file$i; done

kev82 · 09-12-2003, 12:38 PM

by acid_kewpie
try using sprintf()

i think he wants to use c++ strings

best i can think of is

Code:

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

using namespace std;

int main()
{
    ostringstream oss;

    for(int i=0;i<1000;i++) {
        oss.str("");
        oss << "file" << setfill('0') << setw(3) << i;
        //here i print the filename, you should open it.
        cout << oss.str() << endl;
    }

    return 0;
}
~

crabboy · 09-12-2003, 12:43 PM

The C++ way would be to use strstream.

Code:

#include <strstream>
#include <string>


main()
{
   std::string filepre = "file";
   std::string filename;

   int i;
   for ( i = 1; i < 10; i++ )
   {
      strstream s;
      s << i;
      filename = filepre + s.str();
      cout << filename;
   }
}

SaTaN · 09-12-2003, 01:10 PM

I suppose this should do it

#include<stdio.h>
#include<string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
main()
{
int i=0;
char *string="file",my_file[100];
for(i=0;i<10;i++)
{
sprintf(my_file,"%s%d",string,i);
open(my_file,O_CREAT);
}

cash_05 · 09-12-2003, 11:22 PM

Thank you everyone. Really learn somethign good from here.

Actually, i'm trying to write a program/script that can automatic generate many files in sequence. I'm using cbq to control bandwidth for every users in office. I need to define a bandwidht sharper for every ip, those config files will looks like this:

file-0001.ext
----------------
device=eth0,10mbit,1mbit
rate=560Kbit
weight=56Kbit
prio=5
rule=192.168.0.1/32

file-0002.ext
---------------
device=eth0,10mbit,1mbit
rate=560Kbit
weight=56Kbit
prio=5
rule=192.168.0.2/32

....................

file-0254.ext
---------------
device=eth0,10mbit,1mbit
rate=560Kbit
weight=56Kbit
prio=5
rule=192.168.0.254/32

I'm a newbie in linux world, know nothing about sed, only know abit of c++ where i learn from college. I trying to write a program to generate those files instead manually key in.

Can this be done using a shell script instead of program? If so, anyone willing to teach me?

Thanks again.