In c++ how do i check for input error from user?

let say i need to get a number from user.


ex:


double x;


cout %26lt;%26lt;"enter a number \n";


cin%26gt;%26gt;x;


there is cin.fail() to check if the input in a double. however if the user enter "2343.2342dfd" then x will be store as 2343.2342 and cin.fail() is false. "dfd" is still in the string, i can use cin.ignore() to get rid of it , but mainly i want to able to detect the input error of this case.


thanks

In c++ how do i check for input error from user?
use isalpha(x) to check that x IS letters, so use (!isalpha(x)) to check that x IS NOT letters, then also use (isdigit(x)) to check that x IS digits.





what you can do is this:





double x; //declares variable x of type double





do {


cout %26lt;%26lt; "Enter a number: "; //output, input on same line


cin %26gt;%26gt; x;


} while ((isalpha(x)) || (!isdigit(x));








you can also do an if statement to check:





double x;





cout %26lt;%26lt; "Enter a number: ";


cin %26gt;%26gt; x;





if ((isalpha(x)) || (!isdigit(x))) {


cout %26lt;%26lt; "Please enter numbers only! ";


cin %26gt;%26gt; x;


}





although the if statement here only checks once, then kicks out.
Reply:check your input type as integer or double as array() having


0 to 9 if user input contain other than num then it will throw wrong input. use exception handling, i think this will work.

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