#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#define MAX_FILES 50

int openArrayFile( FILE** pFilesArray, const int index, const char* fileName, const char* openMode )
{
char* pHelloWorld = "Hello, World!\n";
int rc = (index >= MAX_FILES ) ? -1 : 0;
if( !rc )
{
pFilesArray[index] = fopen( fileName, openMode );
if( !pFilesArray[index] )
{
rc = errno;
}
fwrite( pHelloWorld, strlen( pHelloWorld ), 1, pFilesArray[index] );
}
return rc;
}

int closeArrayFile( FILE** pFilesArray, const int index )
{
int rc = (index >= MAX_FILES ) ? -1 : 0;
if( !rc )
{
if( !pFilesArray[index] )
{
rc = ERANGE;
}
else
{
rc = fclose( pFilesArray[index] );
if( rc )
{
rc = errno;
}
else
{
pFilesArray[index] = 0;
}
}
}
return rc;
}

int main()
{
int rc = 0;
int i = 0;
char filenameBase[16] = {0};
FILE** pFilesArray = (FILE**)calloc( sizeof( FILE*), MAX_FILES );
if( pFilesArray != NULL )
{
for( i = 1; i < 1+ MAX_FILES; i++ )
{
if( i > 999 )
{
rc = ERANGE;
break;
}
else if( i < 10 )
{
sprintf( filenameBase, "result00%d", i );
}
else if( i < 100 )
{
sprintf( filenameBase, "result0%d", i );
}
else
{
sprintf( filenameBase, "result%d", i );
}
rc = openArrayFile( pFilesArray, -1 + i, filenameBase, "w" );
if( rc )
{
break;
}
else
{
rc = closeArrayFile( pFilesArray, -1 + i );
if( rc )
{
break;
}
}
}
free( pFilesArray );
}
else
{
rc = errno;
}
return rc;
}