Safeguarding scanf() reads as with cin >>. Is this possible?

[wtf]

int x;
backhere:cin >> x;
if (cin.fail())
   {
      cin.clear(); cin.ignore(9999, '\n');
      goto backhere; 
   }

Will catch bad input errors, say if a user enters a char instead of a digit.
But

int x;
scanf("%d", &x);

Will not provide any warnings if the user inputs bad input, and the read will be ignored if say a user enters a char.

How can I make this latter code more robust like the first code?

[Computergeek01]

As a rule of thumb, if you find yourself using "goto" in your C++ code then you are doing something wrong.

I believe the operators on iostream objects are virtualized. You should take the extraction operator attempt to cast the input to the desired data type and if it fails return a null. This way the user can test the input for null instead of this magic "goto-if-then-break" whoi.

[wtf]

You lost me starting with 'virtualized'. Can you provide an example? I'm not sure if I follow you.

[Computergeek01]

Honestly we'd be talking about overloading the primary operator for istream class and it might not have been the best idea for me to jump right at that for a solution in the beginners section.

How about instead of using goto you enter a loop for the user if the fail bit is checked?

[LB]

If cin failed you can't just use it again - you have to use cin.clear() first.

[Alrededor]

The C function scanf() returns an integer which is the number of items successfully read.
See http://cplusplus.com/reference/clibrary/cstdio/scanf/

You could do something like:

int x;
if ( scanf("%d", &x) != 1 )
{
    // Error handling code
}

You probably need to put this in a loop as was also suggest by Computergeek01 for the cin version.

[Computergeek01]

L B is also right though, if the read operation fails the bad character stays in the buffer, you need to clear it before using it again.

[wtf]

How about instead of using goto you enter a loop for the user if the fail bit is checked?

Thats the whole point. Scanf doesn't have a fail bit.

[wtf]

thanks alrededor I will look into it.

Today i've been reading up on stringstreams. Thats not a bit too technical for a beginner is it?