Looks like your depth variable is unset. This means that the expression [ $depth -eq $zero ] becomes [ -eq 0 ] after bash substitutes the values of the variables into the expression. The problem here is that the -eq operator is incorrectly used as an operator with only one argument (the zero), but it … Read more
If you want them to be really equal (i.e. the same items and the same number of each item), I think that the simplest solution is to sort before comparing: Enumerable.SequenceEqual(list1.OrderBy(t => t), list2.OrderBy(t => t)) Edit: Here is a solution that performs a bit better (about ten times faster), and only requires IEquatable, not … Read more
The best implementation? That is a hard question because it depends on the usage pattern. A for nearly all cases reasonable good implementation was proposed in Josh Bloch‘s Effective Java in Item 8 (second edition). The best thing is to look it up there because the author explains there why the approach is good. A … Read more
Different Operators LIKE and = are different operators. Most answers here focus on the wildcard support, which is not the only difference between these operators! = is a comparison operator that operates on numbers and strings. When comparing strings, the comparison operator compares whole strings. LIKE is a string operator that compares character by character. … Read more
It’s entirely likely that a large portion of the developer base comes from a Java background where using == to compare strings is wrong and doesn’t work. In C# there’s no (practical) difference (for strings) as long as they are typed as string. If they are typed as object or T then see other answers … Read more
If you’re looking for efficiency, use this: string.Equals(val, “astringvalue”, StringComparison.OrdinalIgnoreCase) Ordinal comparisons can be significantly faster than culture-aware comparisons. ToLowerCase can be the better option if you’re doing a lot of comparisons against the same string, however. As with any performance optimization: measure it, then decide!
To answer the precise question “Why doesn’t Set provide an operation to get an element that equals another element?”, the answer would be: because the designers of the collection framework were not very forward looking. They didn’t anticipate your very legitimate use case, naively tried to “model the mathematical set abstraction” (from the javadoc) and … Read more
The JPA 2.0 Specification states that: The entity class must have a no-arg constructor. It may have other constructors as well. The no-arg constructor must be public or protected. The entity class must a be top-level class. An enum or interface must not be designated as an entity. The entity class must not be final. … Read more
Joshua Bloch says on Effective Java You must override hashCode() in every class that overrides equals(). Failure to do so will result in a violation of the general contract for Object.hashCode(), which will prevent your class from functioning properly in conjunction with all hash-based collections, including HashMap, HashSet, and Hashtable. Let’s try to understand it … Read more
The theory (for the language lawyers and the mathematically inclined): equals() (javadoc) must define an equivalence relation (it must be reflexive, symmetric, and transitive). In addition, it must be consistent (if the objects are not modified, then it must keep returning the same value). Furthermore, o.equals(null) must always return false. hashCode() (javadoc) must also be … Read more