Direct casting vs 'as' operator?

Question

Consider the following code:

void Handler(object o, EventArgs e)
{
   // I swear o is a string
   string s = (string)o; // 1
   //-OR-
   string s = o as str         


        

Answer 1

I would like to attract attention to the following specifics of the as operator:

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/as

Note that the as operator performs only reference conversions, nullable conversions, and boxing conversions. The as operator can't perform other conversions, such as user-defined conversions, which should instead be performed by using cast expressions.