Equals object ; string overrides this method and performs an ordinal comparison on the string content. See msdn. So read the compile-time warnings! If I remember correctly, the warning text suggests just that. Even better: turn on the warnings-as-errors option to force everyone to pay attention to them. Show 2 more comments. Active Oldest Votes.
Improve this answer. Unless the operator is specifically implemented in the class — Dominic Cronin. DominicCronin This isn't true. It looks like operator overloads are determined at compile time and at compile time all it knows is that the left hand side is an object.
They are quite different which is why. To be clear, object type notice the monospace font is technically meant to be "an expression of type System. Object ". It does not have anything to do with the runtime type of the instance that is referred to by the expression. I think the statement "user-defined operators are treated like virtual methods" is extremely misleading. They are treated like overloaded methods and only depend on the compile-time type of the operands. In fact, after the set of candidate user-defined operators is computed, the rest of the binding procedure will be exactly the method overload resolution algorithm — mmx.
DominicCronin The misleading part is that virtual method resolution depend on the actual runtime type of an instance, whereas that is completely ignored in operator overload resolution, and that is indeed the whole point of my answer. Show 8 more comments. AustinWBryan 3, 3 3 gold badges 18 18 silver badges 37 37 bronze badges.
Spot on. Equals compares object content deep comparison. As mehrdad said,. Equals is overridden to provide that deep content comparison. So String is a bad example to use here, as it doesn't help us understand the general case where no custom operator has been defined. And touches well on string interning. When multiple string literals are identical, the compiler is smart enough to use the same address for both references because strings in.
NET are immutable. Show 7 more comments. When I'm working with a new type whose definition is in flux or writing generic algorithms, I find the best practice is the following If I want to compare references in C , I use Object. Amen Jlili 1, 2 2 gold badges 22 22 silver badges 51 51 bronze badges. JaredPar JaredPar k gold badges silver badges bronze badges. On the other hand, I can see where this stems from and why it might be desirable to make the semantics explicit.
It's short and unambiguous. Konrad, I really should have said "when I'm unfamiliar with a type, i find the best practice is the following". Yes VB has much better semantics here because it truly separates value and reference equality.
C mixes the two together and it occasionally causes ambiguity errors. This is not entirely true. It can only be overloaded, which is an important difference. Here is an actual link for now to the mentioned article: docs. Add a comment. If operands are Reference Types with exception of string and both refer to the same instance same object , it returns true else false.
If operands are string type and their values are equal, it returns true else false. Equals If operands are Reference Types , it performs Reference Equality that is if both refer to the same instance same object , it returns true else false.
Robert Synoradzki 1, 11 11 silver badges 17 17 bronze badges. This is not correct. Describing a special-case exception only for string misrepresents the operator's semantics. It would be more accurate, though perhaps not terribly useful, to say "if operands are reference types it returns true if the operands refer to the same object, unless there is an applicable overload, in which case the implementation of that overload determines the result".
The same is true for Equals with the added complication that it is a virtual method, so its behavior can be overridden as well as overloaded. Equals compares object content. String datatypes always act like content comparison. I hope I'm correct and that it answered your question. Yousha Aleayoub 3, 4 4 gold badges 44 44 silver badges 59 59 bronze badges.
Firstly, there is a difference. Equals 2. Colonel Panic Colonel Panic k 76 76 gold badges silver badges bronze badges. For example, should Comparisons among integral types are fine, but floating-point comparisons should only be performed IMHO with values that are explicitly cast to matching types. Copy Code. Technical based. Value types. Content based Comparison.
Reference based Comparison. String with no interning. Type checking. Above printf statement will print 1. Above printf statement will print 2 and value of var becomes 1. Toggle navigation Home. What is the difference between pre decrement operator --var and post decrement operator var Labels: C , C Interview Questions.
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