Check if input is a number and if not input again

Question

I trying something really simple but in same time a little bit hard for me. I want to let user to insert number via console and if is not number to tell that is not and give chance to insert again while is number. Here is what I've made so far

int a;

 cout<<"enter a: ";
 cin>>a;
 while (!isdigit(a)); {
    cout << "\n ERROR, enter a number" ;
    cin.clear();
    cin >> a;
 }

system("Pause");
return 0;

Now I get error that is not number but the program is terminate. I can't insert again and must start it again.

Related http://stackoverflow.com/questions/19018294/c-to-check-if-user-input-is-a-number-not-a-character-or-a-symbol?rq=1 — Brainless Box, May 14 '14 at 13:56
A number is not a digit. It consists of digits, and sometimes more. You should look at duplicate questions. — luk32, May 14 '14 at 13:57
Your life will be happier if you always initialize variables. — Daniel Daranas, May 14 '14 at 14:13
Thank you @BrainlessBox .. this thread helped me to resolve my problem! — Gordon, May 15 '14 at 05:52

score 2 · Answer 1 · answered May 14 '14 at 14:12

2

Remove the ; from the while line...

Then take care of the value you are testing for beeing a digit – isdigit expects a character, while you're providing the whole integer read from input (say, 57204, which is not a character code).

answered May 14 '14 at 14:12

CiaPan

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Check if input is a number and if not input again

1 Answers1