C: Best way to read an entire text file and putting it in a *char.

Claus · 03-15-2004, 09:42 AM

Hi

I'm developing a GTK+ Text Editor to learn something more about this toolkit.

I'd like to know a good way to read a text file and store it in a *char. At this moment i'm using for this the following piece of code:

Code:

		file = fopen (argv[1], "r");
		string = g_string_new (NULL);
		
		while (!feof (file)){	
			fgets (text, 1000, file);
			g_string_append (string, text);
		}
		fclose (file);
		buffer = string->str;
		g_string_free (string, FALSE);

But with some text files the program crashes.

Is there any other way to read an entire file or line by line safety?

Thank you.

entire program:

Code:

 
#include <stdio.h>
#include <gtk/gtk.h>

GtkWidget *
create_main (char *text)
{
   	GtkWidget *window;
	GtkWidget *button;
	GtkWidget *vbox;
	GtkWidget *textview;
	GtkTextBuffer *buffer;

	window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
	gtk_window_set_default_size (GTK_WINDOW (window), 600, 400);
	gtk_window_set_title ( GTK_WINDOW (window), "CSV's Text Editor");
	g_signal_connect (G_OBJECT (window), "destroy",
			  G_CALLBACK (gtk_main_quit), NULL);
	
	textview = gtk_text_view_new ();
	buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (textview));
	gtk_text_buffer_set_text (buffer, text, -1); 
	
	vbox = gtk_vbox_new (TRUE, 0);
	gtk_container_add (GTK_CONTAINER (window), vbox);
	gtk_box_pack_start (GTK_BOX (vbox), textview, TRUE, TRUE, 0);
	gtk_widget_show_all (vbox);
		
	return window;
}

int main(int  argc,
	 char *argv[])
{
	GtkWidget *window;
	FILE *file;
	char *text = (char *) malloc (1000*sizeof (char));
	char *buffer;
	GString *string;

	gtk_init (&argc, &argv);

	if (argc > 1){
		file = fopen (argv[1], "r");
		string = g_string_new (NULL);
		
		while (!feof (file)){	
			fgets (text, 1000, file);
			g_string_append (string, text);
		}
		fclose (file);
		buffer = string->str;
		g_string_free (string, FALSE);
	}
	else 
		buffer = NULL;

	window = create_main (buffer);

	gtk_widget_show (window);

		
	gtk_main ();
    
	return 0;
}

Claus · 03-15-2004, 10:01 AM

by the way, to compile it use:

gcc -o edit `pkg-config --cflags --libs gtk+-2.0` edit.c

bigearsbilly · 03-15-2004, 10:13 AM

Nothing obvious.
do you know where it crashes?

do you get a core file?
have you gdb'd the core file to find the crash?

billy

billy

Mara · 03-15-2004, 10:16 AM

It's not a good idea to read the whole file. Imagine what can happen if your file is 100MB. I'd rather make a dynamic buffer (with defined max size and procedures what to do when it's reached) and read the amount of data needed at the moment.

hiteshmaisheri · 03-15-2004, 10:18 AM

thanks for the information....

bigearsbilly · 03-15-2004, 10:22 AM

I should imagine maybe that's what Gstring does?
not sure though!

billy

Claus · 03-15-2004, 10:22 AM

I dont care too much about the crash, i'm interesed in different ways to read strings from files.

Thank you all..

bigearsbilly · 03-15-2004, 10:30 AM

Well, how about not doing it?
I had to do a read and substitute file parser.
I didn't bother with that, keep it simple.

Open the file and copy it to another.
then re-open the copy again for rw and using, ftell(), fseek(), fgetc and fputc(), you can navigate in the
copied file, change it and let the standard libraries worry about the buffering and such.

just another approach maybe?

billy

itsme86 · 03-15-2004, 01:22 PM

I use the return value from fgets() instead of feof().

Code:

char *read_file(FILE *fp)
{
  char *str = malloc(4096), *s = str;
  int len = 0;

  while(fgets(s, 4096, fp))
  {
    len += strlen(s);
    str = realloc(str, len+4096);
    s = str+len;
  }
}