# V663\. Infinite loop is possible\. The 'cin\.eof\(\)' condition is insufficient to break from the loop\. Consider adding the 'cin\.fail\(\)' function call to the conditional expression\.

The analyzer has detected a potential error that may lead to an infinite loop\. When you deal with the 'std::istream' class, calling the 'eof\(\)' function is not enough to terminate the loop\. If data reading fails, a call of the 'eof\(\)' function will always return 'false'\. You need an additional check of the value returned by the 'fail\(\)' function to terminate the loop in this case\.

Have a look at an example of incorrect code:

```cpp
while (!cin.eof())
{
  int x;
  cin >> x;
}
```

You can fix the error by making the condition a bit more complex:

```cpp
while (!cin.eof() && !cin.fail())
{ 
  int x;
  cin >> x;
}
```

However, this option has drawbacks\. Correct and the simplest code version looks as follows: 

```cpp
int x;
while(cin >> x) {
  ....;
}
```

Check out a more detailed discussion on reading from the stream here: [Why is iostream::eof inside a loop condition \(i\.e\. 'while \(\!stream\.eof\(\)\)'\) considered wrong?](https://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-i-e-while-stream-eof-cons)