equals-operator

For the code below public struct Person { public int ID; public static bool operator ==(Person a, Person b) { return a.Equals(b); } public static bool operator !=(Person a, Person b) { return !a.Equals(b); } } Why does the compiler give me these warnings? What's wrong with not defining the methods below? warning CS0660: 'Person' defines operator == or operator != but does not override Object.Equals(object o) warning CS0661: 'Person' defines operator == or operator != but does not override Object.GetHashCode() EDIT : This answer has been corrected, among other things to note that user-defined

I am trying to establish equality of three equal variables, but the following code is not printing the obvious correct answer which it should print. Can someone explain, how the compiler is parsing the given if(condition) internally? #include<stdio.h> int main() { int i = 123, j = 123, k = 123; if ( i == j == k) printf("Equal\n"); else printf("NOT Equal\n"); return 0; } Output: manav@workstation:~$ gcc -Wall -pedantic calc.c calc.c: In function ‘main’: calc.c:5: warning: suggest parentheses around comparison in operand of ‘==’ manav@workstation:~$ ./a.out NOT Equal manav@workstation:~$ EDIT:

What is the difference between == and Equals() with example? I know that == is used to compare operator and Equals() method is used to compare content of string.So i tried // first example string s1 = "a"; string s2 = "a"; Console.Write(a.Equals(s2)); // returns true, but if I assign "b" to s2, // then result will be false // second example string s1 ="a"; string s2 ="a"; Console.Write(s1 == s2); // returns true How this is so? Both are different object references. Suppose we consider that these are reference. But I tried to use like this string s1 = new string("ab"); string s2 = new string(

I saw a couple of questions here on SO, with ansers including the function isEqual: instead of the standard == . So far, I have only learned to use the == , so I'm wondering what's better to use, what are the pros and cons of each? When should you use them? Thank you. They do different things; so you need to use the appropriate one: Consider, if you will: NSString *a = @"Hello!"; NSString *b = a; NSString *c = [a mutableCopy]; if (a == b) NSLog(@"This prints"); if (b == c) NSLog(@"This doesn't"); if ([a isEqual:c]) NSLog(@"This does"); In other words; == merely checks if two pointers point to

As the title says: do I need to override the == operator? how about the .Equals() method? Anything I'm missing? An example from msdn public struct Complex { double re, im; public override bool Equals(Object obj) { return obj is Complex && this == (Complex)obj; } public override int GetHashCode() { return re.GetHashCode() ^ im.GetHashCode(); } public static bool operator ==(Complex x, Complex y) { return x.re == y.re && x.im == y.im; } public static bool operator !=(Complex x, Complex y) { return !(x == y); } } You should also implement IEquatable<T>. Here is an excerpt from Framework Design