The process of converting one type to another is called type conversion. In C#, you can perform the following kinds of conversions:
- Implicit conversions
- Explicit conversions
- User-defined conversions
- Conversion with a helper class
To go more in detail about Implicit and Explicit conversions read my previous article Boxing and Unboxing in C#.
Implicit conversions
An implicit conversion doesn’t need any special syntax, it can be executed because the compiler knows that the conversion is allowed and that it’s safe to convert.
A value type such as int can be stored as a double because an int can fit inside a double without losing any precision or from a reference type to one of its base types.
In this example, num is int and will be converted to double and no data will be lost.
int num = 123456;
double bigNum = num;
Console.WriteLine("bigNum: {0}", bigNum);
/* Output:
bigNum: 123456
*/
Also for reference types, no special syntax is necessary because a derived class always contains all the members of a base class. In these cases, the cast is done implicitly by the compiler.
Rectangle rectangle = new Rectangle(); Shape shape = rectangle;