cin's input buffer

[aegis]

Consider the following:

#include <iostream>
#include <string>

using namespace std;

int main(void)
{
int a, b, c;
cin >> a; cin >> b; cin >> c;
string s;
getline(cin, s);
return 0;
}

is there a newline hanging around cin's input buffer
for getline to accept and return immediately?

Because that is how the programming is behaving.

[Alf P. Steinbach]

* aegis:

> Consider the following:
>
> #include <iostream>
> #include <string>
>
> using namespace std;
>
> int main(void)
> {
> int a, b, c;
> cin >> a; cin >> b; cin >> c;
> string s;
> getline(cin, s);
> return 0;
> }
>
> is there a newline hanging around cin's input buffer
> for getline to accept and return immediately?

Yes.

However, 'getline' consumes a newline.

Cheers & hth.,

- Alf

[Juha Nieminen]

aegis wrote:
> cin >> a; cin >> b; cin >> c;

Btw, what's wrong with "cin >> a >> b >> c;"?

[James Kanze]

On Aug 30, 6:32 am, aegis <ae...@mad.scientist.com> wrote:
> Consider the following:

> #include <iostream>
> #include <string>

> using namespace std;

> int main(void)
> {
> int a, b, c;
> cin >> a; cin >> b; cin >> c;
> string s;
> getline(cin, s);
> return 0;
> }

> is there a newline hanging around cin's input buffer
> for getline to accept and return immediately?

Probably. If you're reading from a console, most systems won't
pass the program anything until there is a new line, so the code
can't read the value for c until a new line is entered following
it. And of course, reading an int doesn't remove that new line.

The function getline doesn't necessarily look for a new line of
text; it can't know that you've already read characters from the
current line, so it simply reads from where you are up to (and
including) the next new line character.

--
James Kanze (GABI Software) email:james...@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
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[aegis]

On Aug 30, 6:35 am, James Kanze <james.ka...@gmail.com> wrote:
> On Aug 30, 6:32 am, aegis <ae...@mad.scientist.com> wrote:
>
> > Consider the following:
> > #include <iostream>
> > #include <string>
> > using namespace std;
> > int main(void)
> > {
> >   int a, b, c;
> >   cin >> a; cin >> b; cin >> c;
> >   string s;
> >   getline(cin, s);
> >   return 0;
> > }
> > is there a newline hanging around cin's input buffer
> > for getline to accept and return immediately?
>
> Probably.  If you're reading from a console, most systems won't
> pass the program anything until there is a new line, so the code
> can't read the value for c until a new line is entered following
> it.  And of course, reading an int doesn't remove that new line.
>
> The function getline doesn't necessarily look for a new line of
> text; it can't know that you've already read characters from the
> current line, so it simply reads from where you are up to (and
> including) the next new line character.
>

Is there a preferred/standard way of discarding cin's input buffer?

[aegis]

Seems I want cin.ignore(). Thanks for the responses!