#1,046 – Implicit vs. Explicit Conversions

A conversion occurs in C# when you convert an expression of one type to a different type.  Often this occurs when you convert an instance of one type to an instance of another type.

Conversions can generally be broken down into two categories:

• Implicit
  • Conversion can happen automatically
  • Guaranteed to succeed
  • No loss of data
• Explicit
  • Requires a cast operator
  • Required when either chance of failure or when there will be data loss

Below are some examples of both numeric and reference conversions, implicit and explicit.

            int anInt = 12;

            // Implicit numeric conversion
            long aLong = anInt;

            // Explicit numeric conversion
            int newInt = (int)aLong;

            BorderCollie kirby = new BorderCollie("Kirby", 12);

            // Implicit reference conversion
            // - derived class to base class
            Dog d = kirby;

            // Explicit reference conversion
            // -  base class to derived class, may fail
            // (This example will throw an InvalidCastException
            //  because we're trying to convert a BorderCollie to a
            //  Terrier).
            Terrier t = (Terrier)d;