equality

Curiously: >>> a = 123 >>> b = 123 >>> a is b True >>> a = 123. >>> b = 123. >>> a is b False Seems a is b being more or less defined as id(a) == id(b) . It is easy to make bugs this way: basename, ext = os.path.splitext(fname) if ext is '.mp3': # do something else: # do something else Some fnames unexpectedly ended up in the else block. The fix is simple, we should use ext == '.mp3' instead, but nonetheless if ext is '.mp3' on the surface seems like a nice pythonic way to write this and it's more readable than the "correct" way. Since strings are immutable, what are the technical details of

I've a situation where I need to check whether multiple variables are having same data such as var x=1; var y=1; var z=1; I want to check whether x==1 and y==1 z==1 (it may be '1' or some other value). instead of this, is there any short way I can achieve same such as below if(x==y==z==1) Is this possible in C#? KennyTM is correct, there is no other simpler or more efficient way. However, if you have many variables, you could also build an array of the values and use the IEnumerable.All method to verify they're all 1. More readable, IMO. if (new[] { v1, v2, v3, v4, v5, v6, v7, v8, v9, v10 }

Other than stepping through the elements one by one, how do I compare two lists of strings for equality (in .NET 3.0): This fails: // Expected result. List<string> expected = new List<string>(); expected.Add( "a" ); expected.Add( "b" ); expected.Add( "c" ); // Actual result actual = new List<string>(); actual.Add( "a" ); actual.Add( "b" ); actual.Add( "c" ); // Verdict Assert.IsTrue( actual == expected ); dahlbyk Many test frameworks offer a CollectionAssert class: CollectionAssert.AreEqual(expected, actual); E.g MS Test JaredPar Try the following var equal = expected.SequenceEqual(actual);

Can someone please explain to me why the output from the following code is saying that arrays are not equal ? int main() { int iar1[] = {1,2,3,4,5}; int iar2[] = {1,2,3,4,5}; if (iar1 == iar2) cout << "Arrays are equal."; else cout << "Arrays are not equal."; return 0; } if (iar1 == iar2) Here iar1 and iar2 are decaying to pointers to the first elements of the respective arrays. Since they are two distinct arrays, the pointer values are, of course, different and your comparison tests not equal. To do an element-wise comparison, you must either write a loop; or use std::array instead std::array

Possible Duplicate: php == vs === operator An easy answer for someone I'm sure. Can someone explain why this expression evaluates to true? (1234 == '1234 test') Lucas Green Because you are using the == (similarity) operator and PHP is coercing the string to an int. To resolve it use the === (equality) operator, which checks not only if the value is the same, but also if the data type is the same, so "123" string and 123 int won't be considered equal. In PHP (and JavaScript -- which has slightly different behavior), the comparison operator == works differently than it does in strongly-typed

I want to compare two strings for equality in Java, when either or both could be null , so I cannot simply call .equals() . What is the best way? boolean compare(String str1, String str2) { ... } Edit: return ((str1 == str2) || (str1 != null && str1.equals(str2))); This is what Java internal code uses (on other compare methods): public static boolean compare(String str1, String str2) { return (str1 == null ? str2 == null : str1.equals(str2)); } Since Java 7 you can use the static method java.util.Objects.equals(Object, Object) to perform equals checks on two objects without caring about them