Hi, This is possible, when the file mentioned is not present in the corresponding path or the file name is wrong you get the file handle as -1. And its crashing because, you are trying to close a invalid file handle in close() api.

Hi moonstalker, Here is the solution for your problem,

#include "stdafx.h"
#include <string>

int _tmain(int argc, _TCHAR* argv[])
{
FILE *fHnd = fopen("C:\\sample.txt", "r+");

char \*pBuffer = new char\[5\];
for (int nFileCnt = 0; nFileCnt < 10; nFileCnt++)
{
    std::string strFileName = "";
    sprintf((char \*)strFileName.c\_str(), "C:\\\\File%d.txt", nFileCnt);
    FILE \*fHndWrite = fopen(strFileName.c\_str(), "a+");
    for (int nCnt = 0; nCnt < 10; nCnt++)
    {
        fgets(pBuffer, 5, fHnd);
        fwrite(pBuffer, 1, 3, fHndWrite);
    }
    fclose(fHndWrite);
}
fclose(fHnd);

return 0;

}

In this code assuming you keep your numbers in the file "Sample.txt" file and after you run the code you will get 10 files generated with the names such as File0, File1 etc. Each of these files consist of 10 numbers. Bye.