Thread: File Copying function

Hi everyone,
I wrote a programme to copy the contents of one file into another and I agree that I wrote some useless and extra code. The programme works fine except that it adds an extra ÿ at the end of the file that it copies contents to.

Here's the code:

Code:

#include <stdio.h>
#include <unistd.h>

void fcp(FILE *fp, FILE *sfp);

int main (int argc, char *argv[])
{
	FILE *fp;
	FILE *sfp;
	char c, h;
	int x;

	if (argc < 2)
	{
		printf("Proper Usage:\n./D20Exc5 <FILENAME1> <FILENAME2>\n");
		return 0;
	}
	if ((fp = fopen(argv[1], "r")) == NULL)
	{
		printf("ERROR Opening file %s.\n", argv[1]);
		return 1;
	}
	if ((sfp = fopen(argv[2], "w+")) == NULL)
	{
		printf("ERROR Opening file %s.\n", argv[2]);
		return 1;
	}
	fcp(fp, sfp);
	for (x = 0; !feof(fp); x++)
	{
		fseek(fp, x, SEEK_SET);
		fseek(sfp,x, SEEK_SET);
		c = fgetc(fp);
		h = fgetc(sfp);
		if (c != h)
		{
			puts("Failed Copying Files...");
			puts("Trying Again...");
			puts("Press Ctrl-C to stop at anytime.");
			execl("/home/rhodium/C/Day20/D20Exc5", "fcp", 
					argv[1], argv[2]);
		}
	}
	fclose(fp);
	fclose(sfp);
	return 0;
}

void fcp(FILE *fp, FILE *sfp)
{
	char c;
	while(!feof(fp))
	{
		c = fgetc(fp);
		putc(c, sfp);
	}
}

Could someone tell me why that extra character is at the end of the file and how to remove it?

Thank you

Thanx, Pedro: It is solved.
Could you explain to me what the problem was!?
I mean, in my old way, shouldn't the programme first check for end of file and then copy a character? I don't really understand the difference between your code and mine except for the position of feof() and I don't understand how it can make a difference. So could you please explain it to me?

Thanx

Originally posted by pedro_velho
sorry for the last reply the anwser is here, (i have some dumbness while typing tab key)?:
Use spaces instead

Code:

//alternate way
    while(1)
    {
        c = fgetc(fp);
        if(feof(fp) != 0) break;
        putc(c, sfp);
    }

Are you sure the last byte is output in this case? It looks to me that on last byte this code:
1) reads the last byte which sets EOF
2) check EOF and exit skipping the putc()

How about:

Code:

    do
    {
        c = fgetc(fp);
        putc(c, sfp);
    }  while(feof(fp));

Well, as I said I don't really understand the difference that Pedro's code makes but it works perfectly.

Originally posted by WaltP

Code:

do
    {
        c = fgetc(fp);
        putc(c, sfp);
    }  while(feof(fp));

It seems to me like this code will only copy the first character because after it does, feof(fp) is not TRUE and the loop quits. Correct me if I'm totally off.

Read the FAQ to understand your problem. Then, rewrite your code correctly:

Code:

int c;
while ((c = fgetc(fp)) != EOF)
    fputc(c, sfp);
/* Now use feof() and/or ferror() to determine stream status */