void batch()
{
FILE *originals ;
FILE *output ;
char file_input[50];
char file_output[50];
printf("input numbers filename?\n");
scanf("%s", &file_input);
printf("output numbers filename?\n");
scanf("%s", &file_output);
originals = fopen(file_input, "r");
output = fopen(file_output, "a");
char ean_str[14], isbn_str[11];
int ean[14], i;
while (fgets(ean_str, 14, originals))
{
fputc(13, output);
/*use custom conversion function to make an int array from the input */
for (i=0; i<=12; i++)
{
ean[i] = get_digit(ean_str[i]);
}
/*convert the EAN number to an ISBN and convert the returned integer to a string*/
sprintf(isbn_str, "%07d", ean_to_isbn(ean));
/*write the string to the output file specified*/
fputs(isbn_str, stdout);
/*write a newline to the file*/
fputc(13, stdout);
}
fclose(originals);
fclose(output);
printf("done!\n");
}