C＃中的Nullsafe导航[重复]

var hasNullValue = false;
var x = string.Empty;
var node = firstNode;

while (node.Child != null)
{
    // On the first hit we set the null flag
    // and break out of the loop
    if (node.Value == null)
    {
        hasNullvalue = true;
        break;
    }

    node = node.Child;
}

if (!hasNullValue)
    x = node.Value;