There is a predefined implicit conversion from int to long, float, double, or decimal. For example:
// '123' is an int, so an implicit conversion takes place here:
float f = 123;
There is a predefined implicit conversion from sbyte, byte, short, ushort, or char to int. For example, the following assignment statement will produce a compilation error without a cast:
long aLong = 22;
int i1 = aLong; // Error: no implicit conversion from long.
int i2 = (int)aLong; // OK: explicit conversion.
Notice also that there is no implicit conversion from floating-point types to int. For example, the following statement generates a compiler error unless an explicit cast is used:
int x = 3.0; // Error: no implicit conversion from double.
int y = (int)3.0; // OK: explicit conversion.
For more information on arithmetic expressions with mixed floating-point types and integral types, see float and double.