Taking input, (cin) stopped in the middle

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I dont understand what happened to (cin), see my code:

C++

#include <iostream>
int main()
{
	 int num;
	 do
	 {
		 cout<<"sdjlsdklsdf";
		 cin >>num;
	 }while (num!=100);

return 0 ;
}

If a number is entered, the program run fine. But the problem happens when a character is entered, try it your self.
The (cin) stop functioning!!.

Anyone has any idea?

Posted 4-Mar-11 23:43pm

Abudreas

Updated 5-Mar-11 0:09am

Sandeep Mewara

v2

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2 solutions

Solution 1

Looks like 'num' is declared an integer and so until unless you enter a number it does not move ahead.

Give your cout message properly that one needs to input a number to move ahead.

Posted 5-Mar-11 0:11am

Sandeep Mewara

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CPallini · Accepted Answer · 2011-03-05T00:36:00

Solution 2

cin is working properly, of course. Your code , on the other hand, wrongly assumes that input operation was successfully completed. Try this fix:

C++

#include <iostream>
using namespace std;
int main()
{
     int num;
     do
     {
         cout<<"sdjlsdklsdf";
         cin >>num;
     if (! cin.good()) break;
     }while (num!=100);

return 0 ;
}

Posted 5-Mar-11 0:36am

CPallini

Comments

Andrew Brock 5-Mar-11 7:56am

LOL! 5.

CPallini 5-Mar-11 8:28am

Why thank you, sir. :-)

Sergey Alexandrovich Kryukov 5-Mar-11 23:54pm

I just imagined what OP expected (see my comment below :-) :-))
--SA

Abudreas 5-Mar-11 9:55am

thank you for help.but as i know (char) data type is smaller than (int) (char = 8bit,int=32bit). so you don't need any extra work to convert from (char) to (int).
still i don't understand what the problem.

CPallini 5-Mar-11 10:22am

The cin.good() returns false because the conversion of a string (e.g. "W" or "zass") to a number fails (cin takes a string from the console and tries to convert to a number). That's has nothing to do with char and int sizes.

Abudreas 5-Mar-11 10:44am

OK, thank you , i think i began to understand.

Sergey Alexandrovich Kryukov 5-Mar-11 23:53pm

I with your understanding not "stopped in the middle".
Good luck,
--SA

Sergey Alexandrovich Kryukov 5-Mar-11 23:52pm

Nice explanation in response to such a funny question (I wonder what OP expected as correct behavior in case on invalid numeric string: an educated guess on what the user _wanted_ to enter? :-)
My 5.
--SA

CPallini 6-Mar-11 13:37pm

Thank you. :-)