General C programming question -- extra byte after EOF

[SagaciousKJB]

I've been running across the situation a lot recently where I have to either replace new lines with spaces, or spaces with new lines, to make some hunk of data readable.

I wrote this program that would let me add or subtract lines with '-l' or '-n' respectively, but my problem is that at the end of output, there is always this extra byte, and it's always FF. I can't figure out if this is because it's reading too many bytes or because it's printing too much.

I'm using fgetc() and feof() to test for the EOF, which has worked well for me in the past, and I cannot really see the difference between this implementation of it and some of my other ones. I tried using fseek() and ftell() to get the filesize and use a for() loop, but the problem is that when using stdin instead of an actual file, I wind up getting no data--an incompatibility that I have no idea the cause of.

Anyway, this is the code--some of it might be a little rough, but the Line() and noLine() functions should be obvious.

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

void Line(FILE *in, FILE *out);
void noLine(FILE *in, FILE *out);
void printSyntax(const char programName[]);

int main(int argc, char *argv[])
{
        if(argc > 1 && argc == 2)
        {

                FILE *in=stdin, *out=stdout;

                if(strcmp("-l",argv[1]) == 0)
                        Line(in,out);
                else if(strcmp("-n",argv[1]) == 0)
                        noLine(in,out);
                else
                        printSyntax(argv[0]);

        }
        else if(argc > 1 && argc == 4)
        {
                FILE *in=stdin, *out=stdout;
                if(strcmp("-",argv[2]) != 0)
                        in = fopen(argv[2],"rb");
                if(strcmp("-",argv[3]) != 0)
                        out = fopen(argv[3],"wb");

                if(strcmp("-l",argv[1]) == 0)
                        Line(in,out);
                else if(strcmp("-n",argv[1]) == 0)
                        noLine(in,out);
                else
                        printSyntax(argv[0]);
        }
        else
                printSyntax(argv[0]);

        return 0;
}

void Line(FILE *in, FILE *out)
{
        int byte;

        while(!feof(in))
        {
                        if(!feof(in))
                        {
                                byte = fgetc(in);
                                if(byte == ' ')
                                        fprintf(out,"\n");
                                else
                                        fprintf(out,"%c", byte);
                        }
        }
}

void noLine(FILE *in, FILE *out)
{
        int byte;

                while(!feof(in))
                {
                        if(!feof(in))
                        {
                                byte = fgetc(in);
                                if(byte == 10)
                                        fprintf(out," ");
                                else
                                        fprintf(out,"%c", byte);
                        }
                }
}

void printSyntax(char const programName[])
{
        printf("inputdata | %s [options] | outputprogram : parses inputdata with lines or no lines and sends to program\n%s [options] inputFile[-] outputFile[-] : reads and or writes to file, or '-' to specify stdin or stdout\n", programName, programName);
}

[blinky]

Try changing:

      if(!feof(in))
      {
         byte = fgetc(in);
         if(byte == ' ')
            fprintf(out,"\n");
         else
            fprintf(out,"%c", byte);
      }

to

      byte = fgetc(in);
      if(byte != EOF)
      {
         if(byte == ' ')
            fprintf(out,"\n");
	 else
            fprintf(out,"%c", byte);
      }

[SagaciousKJB]

Try changing:

      if(!feof(in))
      {
         byte = fgetc(in);
         if(byte == ' ')
            fprintf(out,"\n");
         else
            fprintf(out,"%c", byte);
      }

to

      byte = fgetc(in);
      if(byte != EOF)
      {
         if(byte == ' ')
            fprintf(out,"\n");
	 else
            fprintf(out,"%c", byte);
      }

Thanks, that worked well. It had more to do with the placement of

byte = fgetc(in)

though