Question

If x is a value then are the following just syntactically different but effectively the same? Is the second a shortcut for the first?

Convert.ToInt32(x);
(int)x;

Or can one be used in some circumstances over and above the other?

Looking in MSDN it seems that the first is doing something different to the second.

Answer 1

(int) is explicit cast where Convert.ToInt is method

Consider:

string x = "1";
int temp = 0;
temp = Convert.ToInt32(x);
temp = (int)x; //This will give compiler error

Casting works for compatible types:

long l = 123;
int temp2 = (int)l;

double d = 123.2d;
int temp3 = (int)d; // holds only the int part 123

You may see Explicit cast – MSDN

if a conversion cannot be made without a risk of losing information,
the compiler requires that you perform an explicit conversion, which
is called a cast. A cast is a way of explicitly informing the compiler
that you intend to make the conversion and that you are aware that
data loss might occur.