On Wednesday 12 December 2001 5:37 pm, Andre Poenitz wrote:
> On Wed, Dec 12, 2001 at 03:50:46PM +0000, Angus Leeming wrote:
> > Sorry for the off-topic question but:
> >
> > What is the correct way to empty a stringstream to use it again?
Currently,
> > I'm using ss.str(string()) but I'm sure there must be a better way...
>
> Don't do that. Use a new stream.
> I'll never know what flags have been changed.
>
> Andre'
Thanks, André, I'll do that.
Here's a new question for you:
Is there a quick and easy way to go to a particular line in an ifstream?
Eg, grep -n "Some string" data_file
gives me a list of lines containing "Some string". It'd be nice to jump to
each line, but istream::seekg(pos) goes to the char at pos, not to a line.
At the moment I have
int setline(ifstream & in, int desired_line_no)
{
in.seekg(0, ios::beg);
int line_no = 0;
int start_line = -1;
string buffer;
int tellg = 0;
for (;;) {
if (line_no == desired_line_no) {
// success !
start_line = tellg;
break;
}
tellg = in.tellg();
getline(in, buffer);
if (!in.good())
break;
++line_no;
}
return start_line;
}
which takes ages to go to the end of a big file because I read each line into
a string.
Alternatively, can you point me to a good streams reference. I've been unable
to find anything relevant in Stroustrup.
Angus
