Proper Capitalization

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>


int file_eof(FILE *in)  // could use "int *ch" to avoid seeking
{
   if(!in) return -1;
   int c;

   c = fgetc(in);
   if(c == EOF) return 1;

   c = fseek(in, -1, SEEK_CUR);
   if(c != 0)
     return -2;

   return 0;
}


void file_eofHandle(FILE *in)
{
   int c = file_eof(in);

   if(c < 0)
   {
      printf("[-] file_eof() [%d]\n", c);
      exit(1);
   }

   if(c == 1)
     exit(0);  // should use fclose(in), but program termination closes it

   return;
}


int file_previousChar(FILE *in, int *pChar)
{
   if(in == NULL || pChar == NULL)
     return -1;

   long fPos;

   fPos = ftell(in);
   if(fPos < 2)
   { *pChar = 0;
      return 0; }

                             // blah i[]
   fseek(in, -2, SEEK_CUR);  // blah[]i

   *pChar = fgetc(in);       // blah[]i  (gets space)
   fgetc(in);                // blah [i] (gets i, leaves where it left off)

   return 1;
}


int file_nextChar(FILE *in, int *nChar)
{
   if(in == NULL || nChar == NULL)
     return -1;

   *nChar = fgetc(in);

   int r = fseek(in, -1, SEEK_CUR);
   if(r != 0)
     return 0;
   return 1;
}


int word_isLonerI(FILE *in)
{
   if(in == NULL)
     return -1;

   int pChar, nChar;
   int pC, nC;

   pC = file_previousChar(in, &pChar);
   if(pC < 1)
     return 0;

   nC = file_nextChar(in, &nChar);
   if(nC < 1)
     return -2;

   pC = isalpha(pChar);
   if(pC == 0)
   {
      nC = isalpha(nChar);
      if(nC == 0)
        return 1;
   }

   return 0;
}

int main(int argc, char **argv)
{
   FILE *in, *out;
   int c, r;
   int sBegin = 1;  // beginning of sentence

   if(argc < 2)
     return 1;

   in = fopen(argv[1], "r");
   if(!in)
     return 2;

   out = stdout; // there's no need to write to a file
                 // that's what piping is for
                 //  if using *nix system file descriptor, then stdout is 1

   while(1)
   {
      file_eofHandle(in);

      c = fgetc(in);

      if(c == '.')
        sBegin = 1;

      if(isalpha(c) != 0)  // using if((c >= 0xwhatever && c <= 0xwhatever) ||
      {                    //          (blah >= lakjsdflkj...)) is harder to read
                           // and a function should be used anyway
         if(sBegin != 0)
         {
            c = toupper(c);
            fputc(c, out);
            sBegin = 0;
         }
         else if(c == 'i')
         {
            r = word_isLonerI(in);

            if(r < 0)
            {
               fprintf(stderr, "[-] seeking failed\n");
               exit(1);
            }

            if(r == 1)
              fputc((int) 'I', out);
            else
              fputc((int) 'i', out);
         }
         else
            fputc(c, out);
      }
      else
        fputc(c, out);
   }

   return 0;
}