equality

问题 Followind describes an issue I am running into using EF 4.2 and LINQ. I've tried this on multiple systems, and multiple flavors of SQL (SQL Express and SQL 2008 R2 Sp1), VS 2010 Pro and Premium, both in 64 bit and 32 binaries, both with the debugger, and attempting to run the binary directly. I'm wondering what I've stumbled against, if it's an issue with EF, or more likely an issue with my code and I'm missing some nuance either related to LINQ or EF. Any assistance would be greatly

问题 The HOTT book writes on page 51: ... we can prove by path induction on p: x = y that $(x, y, p) =_{ \sum_{(x,y:A)} (x=y)} (x, x, refl x)$ . Can someone show me how to proof this in COQ? Remarks: Sorry that I do not know how to render latex code here. That is not homework. 回答1: Actually, it is possible to prove this result in Coq: Notation "y ; z" := (existT _ y z) (at level 80, right associativity). Definition hott51 T x y e : (x; y; e) = (x; x; eq_refl) :> {x : T & {y : T & x = y} } := match

问题 I'm working on a lecture about hard to understand JavaScript code and of course on of the weak point of JavaScript is knowing what == / === will return. I found this great answer in stack that covers this subject nicely - Which equals operator (== vs ===) should be used in JavaScript comparisons? one of the things that caught my eyes (probably because I wasn't aware of it until now) was that you can use String Objects instead of primitives and you will get different result in your conditions

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Wrapper class and == operator It seems as if object equality operator for wrapper classes produces different results depending on whether the wrapped value is in byte range or not. Here is a code snippet to demonstrate this behavior: System.out.println("smaller than byte"); Integer i1 = 1; Integer i2 = 1; if (i1 == i2) System.out.println("same"); if (i1 != i2) System.out.println("not same"); System.out.println(

问题 I don't understand why Resharper suggest me to "check for reference equality instead" in this code: if ( typeToTranslate.Equals( typeof(string) ) ) { //do something } Why this should be better: typeToTranslate == typeof(string) ------------EDIT------------ This is the method stub: protected IType TranslateType(Type typeToTranslate) { if (typeToTranslate == null) throw new ArgumentNullException("typeToTranslate"); //do some stuff if (typeToTranslate.Equals(typeof(string))) { //do some stuff }

问题 #!/usr/bin/env perl use warnings; use 5.12.2; my $c = 'f'; # could be a number too if ( $c eq 'd' || $c == 9 ) { say "Hello, world!"; } What is the best way, to avoid the 'Argument "f" isn't numeric in numeric eq (==) at ./perl.pl line 7.'-warning? I suppose in this case I could use "eq" two times, but that doesn't look good. 回答1: Not sure why you want to avoid the warning. The warning is telling you that there's a potential problem in your program. If you're going to compare a number with a

问题 i'm still quite new to programming, so please excuse me. I need to do the following: Right now i have a string being output with two value: one with characters and numbers, a comma and the second with just a boolean value. 9fjrie93, 1 I would like to trim the string so it just ourputs as the boolean value. e.g. 1 I then need to perform an equality check on the boolean value. If it's 1 do one thing, else do something else. Would a simple if statement suffuce? Thanks very much 回答1: No need for

问题 This question already has answers here : 2 identical strings “not equal” [Python] (1 answer) Python Two Identical Strings are viewed as Different (1 answer) Closed 8 months ago . I'm trying to write a chat server using python. I am using SHA1 hash to validate users and comparing the stored hash for the user to the hash of the given password and if they are the same then I should validate the user. My hash function looks like this: def sha1_encode(string): import hashlib return hashlib.sha1

问题 The same goes for '1\t' (and probably others). if (1 == '1\n') { console.log('Equal'); } else { console.log('Not Equal'); } 回答1: As said before if you compare number == string , it will automatically try to convert the string to a number. the \n and \t are simply whitespace characters and therefore ignored. This and similar behaviour can be rather confusing leading to situations like this: (Picture taken from: https://www.reddit.com/r/ProgrammerHumor/comments/3imr8q/javascript/) 回答2: The

问题 I'm facing a strange problem in python. I have a maze, x's stand for walls, g is a goal, s is the starting point and the numbers are portals which bring you from one number to the other (e.g. if you go on one of the 2's it will transport you to the other 2). xxxxxxxxxxxxxxxxxxxx x2 x x xxx x x 1 x xxxxx x x s x x x x x xxxxxxx x xx xxxxx x x x g x x 1 x 2 x xxxxxxxxxxxxxxxxxxxx I'm trying to find all portals and put them into an array. So far this works, the program finds all four portals.