How to recover from failing cin.get(str,n,'\n')?

[Alexander Malkis]

How to recover from failing cin.get(str,n,'\n')?
The user pressed "Enter" on cin.get(...).I would like to let him try
once more but the system doesn't stop on the next cin.get. Code:

cin.get(str,n,'\n');
cout<<"haha\n";
char c;
/*
Now get '\n'. Doesn't work if the first time nothing else was input.
Have this line or leave it -it doesn't change the outcome in this case.
*/
cin.get(c);
cin.get(str,n,'\n'); //here doesn't wait if the first time Enter was
pressed.

 

[Mike Wahler]

How to recover from failing cin.get(str,n,'\n')?
The user pressed "Enter" on cin.get(...).I would like to let him try
once more but the system doesn't stop on the next cin.get. Code:

cin.get(str,n,'\n');
cout<<"haha\n";
char c;
/*
Now get '\n'. Doesn't work if the first time nothing else was input.
Have this line or leave it -it doesn't change the outcome in this case.
*/
cin.get(c);
cin.get(str,n,'\n'); //here doesn't wait if the first time Enter was
pressed.

if std::istream::get(T*, std::streamsize, T) does
not extract any elements, it sets std::istream::failbit.
(This function does not extract the delimiter T).
No further i/o will be performed until the stream state
is reset.

#include <ios>
#include <iostream>
#include <limits>


int main()
{
char str[100] = {0};
std::streamsize n(sizeof str);

std::cin.get(str, n, '\n');
std::cout << "one\n";

std::cin.clear();

std::cin.ignore
(std::numeric_limits<std::streamsize>::max(), '\n');

std::cin.get(str, n, '\n');
std::cout << "two\n";


return 0;
}

Rather than a simple 'std::cin.get()' to remove the newline,
I've used 'std::istream::ignore' instead, which will remove
any pending characters, the number of which might have exceeded
the value of the type 'streamsize' argument.

You could avoid all these machinations by using the
'std::getline()' nonmember function declared by <string>,
which stores the input in a 'std::string' object, and
does extract (but does not store) the newline character.

#include <iostream>
#include <string>

int main()
{
std::string line;
std::getline(std::cin, line);
std::getline(std::cin, line);
return 0;
}

-Mike

 

[Mike Wahler]

You could avoid all these machinations by using the
'std::getline()' nonmember function declared by <string>,
which stores the input in a 'std::string' object, and

does extract (but does not store) the newline character.

Should be:

does extract (but does not store) the delimiter
(a newline by default) character.

-Mike

 

[Alexander Malkis]

Should be:

does extract (but does not store) the delimiter
(a newline by default) character.

-Mike

Thanks!

 

[Alexander Malkis]

Actually, I used
cin.getline(char_type* __s, streamsize __n, char_type __delim);
somewhere from std_istream.h