restrict input to integer

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C#

int a[5];
    for(int i=0;i<5;i++)
    {
            cin>>a[i];
    }

The problem is that when we give wrong value in array it takes a garbage value and next iteration cin doesn't take new value from keyboard.
I want to avoid wrong input from keyboard. how is this possible?

e.g.
1
2
f
now "cin" will not take further input from keyboard.

Posted 24-Nov-10 8:00am

bilal haider

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#realJSOP · Answer 1 · 2010-11-24T08:24:00

Solution 1

Well, accept input differently. In other words, validate the incoming data to make sure it's what you want/expect. I'll give you some hints:

0) You don't *have* to accept the data directly into the array

1) The array doesn't *have* to be an array of integers.

Go forth, and code.

Posted 24-Nov-10 8:24am

#realJSOP

Aescleal · Answer 2 · 2010-11-24T09:35:00

It's possible because someone's entering data the program isn't expecting. What's happening here is that when the stream sees the input of a character that isn't convertible to an integer it sets the stream into a fail state. If you want to get it out of the fail state you have to:

- Detect when the stream enters the fail state
- When it does, set the stream to a good state
- Purge the input that put the stream in that state

Each one's about another line of code in your loop. Have a look at your compiler's reference for std::istream and that should point you in the right direction.

Cheers,

Ash

PS: "Standard C++ IO Streams and Locales: Advanced Programmers Guide and Reference" by Kreft and Langer is an invaluable book for using iostreams. It's well worth a buy and one of my most used references, even after using the language for nearly 20 years.

@Intersect☺™ · Answer 3 · 2010-11-24T09:35:00

hi,

I also suggests you the same as above posted comments. Firstly fetch values from keyboard into an Integer then check for the validation. If the input is in between 0 to 9, then assign that value into your integer array. The code might look somewhat as below:

int a[5], x;

for(int i=0; i < 5; i++)
{

cout<< " Pls enter an integer"
cin>> x
if ( !isdigit ( x ) )
cout<< "That is not a valid input \n";
Else
a[i] = x;

}

restrict input to integer

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