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]

cin >> a; cin >> b; cin >> c;

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

 

[James Kanze]

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.

 

[aegis]

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]

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

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