comparison-operators

I know that !== is used to compare variable types too, while != only compares values. But I see that many people use !== when they compare values, for example: $stuff = 'foo'; if($stuff !== 'foo') // do... Is there any reason they do this? Is !== faster than != or what? If you do know in advance that both variables are of the same type, then it won't make any difference. I think the speed difference is just so negligible that the speed argument can (and should) be completely ignored, and you should focus on your application rather than focusing on premature (and unnecessary) optimization.

If I have a type that consists of a single numeric data member (say, an int ) and various methods, is there a convenient way to tell the compiler to automatically generate all the obvious comparison operators? I.e., instead of this (using inline instead of constexpr for C++03, of course): class MyValueType { private: int myvalue; public: constexpr bool operator<(MyValueType rhs) const { return myvalue < rhs.myvalue; } constexpr bool operator>(MyValueType rhs) const { return myvalue > rhs.myvalue; } constexpr bool operator>=(MyValueType rhs) const { return myvalue >= rhs.myvalue; } constexpr

I am working on a section of PHP code for a project that compares a date in the YYYY-MM-DD format to the current date to see if it is less than the current date. At different points in the code two different methods were used for making this comparison. The first used get_timestamp() on the dates and ran the comparison off of the timestamps. In another place it just compared the string of the date to the output from date("Y-m-d") . My expectation was that the comparison of two date strings would not provide a correct response. However, when I set up several test cases I got the output expected

I reviewed the following posts beforehand. Is there a way to use DataFrame.isin() with an approximation factor or a tolerance value? Or is there another method that could? Filter dataframe rows if value in column is in a set list of values use a list of values to select rows from a pandas dataframe EX) df = DataFrame({'A' : [5,6,3.3,4], 'B' : [1,2,3.2, 5]}) In : df Out: A B 0 5 1 1 6 2 2 3.3 3.2 3 4 5 df[df['A'].isin([3, 6], tol=.5)] In : df Out: A B 1 6 2 2 3.3 3.2 You can do a similar thing with numpy's isclose : df[np.isclose(df['A'].values[:, None], [3, 6], atol=.5).any(axis=1)] Out: A B 1

I have the following operator< that is supposed to sort first by a value, then by another value: inline bool operator < (const obj& a, const obj& b) { if(a.field1< b.field1) return true; else return a.field2 < b.field2; } I have the feeling this is incorrect and that you can't do that without another third comparaison test on the members variables, but I can't find any example where this doesn't work. So whould this really sort as expected? thanks edit : I would have coded it as : inline bool operator < (const obj& a, const obj& b) { if(a.field1< b.field1) return true; else if(a.field1> b

There are many cases in which JavaScript's type-coercing equality operator is not transitive. For example, see " JavaScript equality transitivity is weird ." However, are there any cases in which == isn't symmetric ? That is, where a == b is true and b == a is false ? SLaks In Javascript, == is always symmetric . The spec says : NOTE 2 The equality operators maintain the following invariants: A != B is equivalent to !(A == B) . A == B is equivalent to B == A , except in the order of evaluation of A and B . It's supposed to be symmetric. However, there is an asymmetric case in some versions of

This question already has an answer here: Which equals operator (== vs ===) should be used in JavaScript comparisons? 49 answers JavaScript comparison operators: Identity vs. Equality 4 answers Why does the following statement return false in JavaScript? new String('hello') === new String('hello') Pointy Two String objects will always be unequal to each other. Note that JavaScript has string primitive values as well as a String constructor to create wrapper objects. All object equality comparisons (especially with === ) are carried out as a test for reference equality . References to two