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Full Discussion: fgets problems
Top Forums Programming fgets problems Post 302396557 by CRGreathouse on Thursday 18th of February 2010 06:56:07 PM
Old 02-18-2010
Quote:
Originally Posted by jim mcnamara
What Corona was saying - you probably have corrupted stack or heap memory somewhere earlier than the fgets call. This means there may still exist serious data corruption. You are just no longer trashing it to the point it crashes.
Right, that's why it's good I rewrote the earlier portions.

Quote:
Originally Posted by jim mcnamara
Does your output - even though code appears to work - seem odd?
This is fortunately only an I/O routine; no calculations to speak of. And after my rewrite it's quite short:
Code:
#define MAX_VECLEN 10000
#define MAX_LINELEN 1100
GEN
bfilein(char* name)
{
	FILE *f = fopen(name, "r");
	if (!f)
		pari_err(openfiler, "input", name);
	
	GEN v = vectrunc_init(MAX_VECLEN + 1);
	char line[MAX_LINELEN];
	int i = 0;
	while(fgets(line, MAX_LINELEN, f) != NULL) {
		char* kept = getBValue(line);
		GEN value = strtoi(kept);
		if (value == NULL)
			continue;
		if (++i > MAX_VECLEN) {
			pari_warn(warner, "only %d terms used; b-file has unread terms", MAX_VECLEN);
			break;
		}
		vectrunc_append(v, value);
	}
	fclose(f);
	return v;
}

with one helper function:
Code:
char*
getBValue(char* line)
{
	int start = 0;
	while (line[start] == ' ' || line[start] == '\t')
		start++;
	if (line[start] == '#')
		return NULL;	// Comment
	if (line[start] == '-')
		start++;
	while (line[start] >= '0' && line[start] <= '9')
		start++;
	while (line[start] == ' ' || line[start] == '\t')
		start++;
	int end = start;
	if (line[end] == '-')
		end++;
	while (line[end] >= '0' && line[end] <= '9')
		end++;
	if (start == end)
		return NULL;	// Blank line, or no numbers found
	line[end] = '\0';
	
	return line + start;
}

The parser is pretty boneheaded, but this isn't performance-limiting -- usually < 100 kB input.
 

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LEARN ABOUT DEBIAN

geometry::primitive::line

Geometry::Primitive::Line(3pm)				User Contributed Perl Documentation			    Geometry::Primitive::Line(3pm)

NAME

       Geometry::Primitive::Line - A Line

DESCRIPTION

       Geometry::Primitive::Line represents a straight curve defined by two points.

SYNOPSIS

	 use Geometry::Primitive::Line;

	 my $line = Geometry::Primitive::Line->new();
	 $line->start($point1);
	 $line->end($point2);

ATTRIBUTES

   end
       Set/Get the end point of the line.

   start
       Set/Get the start point of the line.

METHODS

   new
       Creates a new Geometry::Primitive::Line

   contains_point
       Returns true if the supplied point is 'on' the line.  Accepts either a point object or an x y pair.

   grow
       Does nothing, as I'm not sure how.  Patches or hints welcome.

   is_parallel ($other_line)
       Returns true if the supplied line is parallel to this one.

   is_perpendicular ($other_line)
       Returns true if the supplied line is perpendicular to this one.

   length
       Get the length of the line.

   point_end
       Get the end point.  Provided for Shape role.

   point_start
       Get the start point.  Provided for Shape role.

   scale
       Does nothing at the moment.

   slope
       Get the slope of the line.

   to_string
       Guess!

   y_intercept
       Returns the Y intercept of this line.

AUTHOR

       Cory Watson <gphat@cpan.org>

COPYRIGHT &; LICENSE
       You can redistribute and/or modify this code under the same terms as Perl itself.

perl v5.10.1							    2010-01-10					    Geometry::Primitive::Line(3pm)
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