Thread: copy data from one file to another

See this FAQ: http://faq.cprogramming.com/cgi-bin/...&id=1043284392

How to copy data from an existent file to a new file inserting a line numbers at the begining of each line?
The original file are paragraphs and I have to copy the paragraphs into another file inserting a line of numbers on each line.

Example:

original file

ibvevbelfvbeflvhbefvbh
uedvheunv
undojvndfojvndfjvndfjvndfj vdfjnvdjfvn dfvjndfv dfvlndfvjdfvn

dfvjefvnef
efgioergerngenfg


copy of the file into the new one

1. ibvevbelfvbeflvhbefvbh
2. uedvheunv
3. undojvndfojvndfjvndfjvndfj vdfjnvdjfvn dfvjndfv dfvlndfvjdfvn
4.
5. dfvjefvnef
6. efgioergerngenfg

and so forth

thanks,

Sometimes you get what you asked for:

Code:

#include <stdio.h>	// for "fprintf" and "fgetc"
#include <stdlib.h>	// for "exit"

	// function prototypes 
void fatal (int retv, char *message);
int streamline (FILE *IN);

char *buffer;		// global buffer

int main (int argc, char *argv[]) {	// argv[1] will be the filename to read
	FILE *fstRO, *fstOUT;		// argv[2] will be the filename to write
	int retv, ln=1; // ln is for line number
	
	if (argc<2) fatal(-1,"Two filenames required.");	// check for them
		
		// open the files
	if ((fstRO=fopen(argv[1],"ro"))==NULL) fatal(-2,"Can't read from file #1.");
	if ((fstOUT=fopen(argv[2],"w"))==NULL) fatal(-2,"Can't write out to file #2.");

	while ((retv=streamline(fstRO))>0) {		// read from file
		fprintf(fstOUT, "&#37;d. %s\n",ln,buffer); 	// write to file
		ln++; 	// increment
		free(buffer);	// very important since buffer had memory allocated in streamline()
	}
	
	switch (retv) {		// finished reading file
		case -2: fatal(-3,"Memory allocation failure!"); 	// in case streamline() fails
		case -1: fprintf(fstOUT, "%d. %s\n",ln,buffer);		// the "special case"
			break;
		case 0:	break;
		default: break;
	}
	free(buffer);	// less important since the program is now over	
		// close the files
	fclose(fstRO);
	fclose(fstOUT);
	return 0;		// THE END
}

void fatal (int retv, char *message) {
	puts(message);
	exit (retv);
}

int streamline (FILE *IN) {	// returns a string length that INCLUDES the line terminator or 0 for last line
	int chr, i=0;		// i is for iteration counter
	buffer=malloc(1);	// begin allocating memory for the line buffer
	while ((chr=fgetc(IN))!=EOF) {
		if (buffer==NULL) return -2;		// in case memory allocation fails
		if (chr=='\n') {	// reached end of line
			buffer[i]='\0';	// so terminate it
			return i+1;
		}
		buffer[i]=chr;		// copy character into buffer
		buffer=realloc(buffer,++i+1);	// more memory for next iteration
	}	// End-Of-File reached
	if (buffer==NULL) return -1;	// last check
	if (i>1) {
		buffer[i]='\0';		// terminate last line if it exists with no newline
		return -1;		// (a normative "special case")
	}
	return 0;		// and return 0 to indicate we're finished
}

Compile as "filecopy" and use:
filecopy filetocopy.txt filetocreat.txt
edit: there's actually three very minor bugs in this, and Salem found them all (see subsequent posts).

Probably a good idea not to mention the bugs then...

Originally Posted by Salem

Probably a good idea not to mention the bugs then...

That's because there aren't any!

Well obviously, because you can't find them!

Is your basis of "bug free" down to "it's produced the correct answer with a few tests, and it hasn't crashed"?

And another attack at MK27, this time Salem, lol

Originally Posted by Matus

And another attack at MK27, this time Salem, lol

I would hardly call it an attack on anything but MK27's code, but in any case, if you dare to call your code bug free, then it better be bug free.

Originally Posted by Salem

Well obviously, because you can't find them!

No, can you?

Originally Posted by Salem

Is your basis of "bug free" down to "it's produced the correct answer with a few tests, and it hasn't crashed"?

No. I would say it appears to run without bugs to me tho.