# V3217\. Possible overflow as a result of an arithmetic operation\.

The analyzer has detected an arithmetic operation that may result in an overflow\.

The example:

```cpp
private const int _halfMaximumValue = int.MaxValue / 2;

public void Calculate(int summand)
{
    int sum;

    if (summand > _halfMaximumValue + 1)
    {
        sum = _halfMaximumValue + summand;
    }

    ....
}
```

In the `Calculate` method, the sum of the passed parameter and the constant is calculated\. The constant is equal to half of the maximum `System.Int32` value\. The parameter value is checked before the addition operation to avoid the arithmetic overflow\. 

However, the condition contains an error\. In this case, there is a check whether `summand` is greater than `_halfMaximumValue + 1`\. If the condition is true, the arithmetic overflow will occur during the addition operation\.

For proper check execution, replace the `>` operator with `<`:

```cpp
private const int _halfMaximumValue = int.MaxValue / 2;

public void Calculate(int summand)
{
    int sum;

    if (summand < _halfMaximumValue + 1)
    {
        sum = _halfMaximumValue + summand;
    }

    ....
}
```

Overflow can occur when using unverified external data as an operand:

```cpp
private const int _halfMaximumValue = int.MaxValue / 2;

public void Calculate()
{
  var numberStr = Request.QueryString["number"];

  if (Int32.TryParse(numberStr, out int number))
  {
    int sum = _halfMaximumValue + number;
    ....
  }
}
```

The `numberStr` value, obtained from the external source, is converted to `int` and assigned to the `number` variable\. Then, `number` is added to `_halfMaximumValue`\. This may lead to an overflow if `number` is greater than half of the maximum `int` value\.

To prevent this overflow issue, limit `number` before performing the addition:

```cpp
private const int _halfMaximumValue = int.MaxValue / 2;

public void Calculate()
{
  var numberStr = Request.QueryString["number"];

  if (   Int32.TryParse(numberStr, out int number)
      && number < 1000) // <=
  {
    int sum = _halfMaximumValue + number;
    ....
  }
}
```