C# difference between == and Equals()

Question

I have a condition in a silverlight application that compares 2 strings, for some reason when I use == it returns false while .Equals()

Answer 1

The == token in C# is used for two different equality-check operators. When the compiler encounters that token, it will check whether either of the types being compared has implemented an equality-operator overload for either the specific combination types being compared(*), or for a combination of types to which both types can be converted. If the compiler finds such an overload it will use it. Otherwise, if the two types are both reference types and they are not unrelated classes (either may be an interface, or they may be related classes), the compiler will regard == as a reference-comparison operator. If neither condition applies, compilation will fail.

Note that some other languages use separate tokens for the two equality-check operators. In VB.NET, for example, the = token is used within expressions solely for the overloadable equality-check operator, and Is is used as a reference-test or null-test operator. An to use = on a type which does not override the equality-check operator will fail, as will attempting to use Is for any purpose other than testing reference equality or nullity.

(*)Types generally only overload equality for comparison with themselves, but it may be useful for types to overload the equality operator for comparison with other particular types; for example, int could have (and IMHO should have but didn't) defined an equality operators for comparison with float, so that 16777217 would not report itself equal to 16777216f. As it is, since no such operator is defined, C# will promote the int to float, rounding it to 16777216f before the equality-check operator sees it; that operator then sees two equal floating-point numbers and reports them as equal, unaware of the rounding that took place.