Why use Convert.ToInt32 over casting? [duplicate]

Question

A question cropped up at work today about how to convert an object into its specific type (an int), I said to cast it:

int i = (int)object;

a colleague said to use Convert.ToInt32().

int i = Convert.ToInt32(object)

What's the difference between Convert.ToInt32() and a direct object cast?

Answer 1

Not every object can be cast directly to int. For example, the following will not compile:

string s = "1";
int i = (int)s;

because string is not implicitly convertible to int.

However, this is legal:

string s = "1";
int i = Convert.ToInt32(s);

As a side note, both casting and Convert can throw exceptions if the input object cannot be converted. However, int.TryParse does not throw if it fails; rather, it returns false (but it only takes in a string, so you have to .ToString() your input object before using it):

object s = "1";
int i;
if(int.TryParse(s.ToString(), out i))
{
   // i now has a value of 1
}