comparison

问题 For my answer in this question I have to compare two characters. I thought that the normal char.CompareTo() method would allow me to specify a CultureInfo , but that's not the case. So my question is: How can I compare two characters and specify a CultureInfo for the comparison? 回答1: There is indeed a difference between comparing characters and strings. Let me try to explain the basic issue, which is quite simple: A character always represents a single unicode point. Comparing characters

问题 Is the following piece of code supposed to work? bool b1 = true; bool b2 = 1 < 2; if (b1 == b2) { // do something } I suspect that not all 'trues' are equal. 回答1: Yes. All trues are equal. 回答2: Yes, boolean values can only store true or false, and you can compare the values for equality. However, some bad uses of bool variables can lead to "undefined" behaviours and might look as if it is neither true nor false. For example reading the value of an uninitialized automatic variable or direct

问题 Is the following piece of code supposed to work? bool b1 = true; bool b2 = 1 < 2; if (b1 == b2) { // do something } I suspect that not all 'trues' are equal. 回答1: Yes. All trues are equal. 回答2: Yes, boolean values can only store true or false, and you can compare the values for equality. However, some bad uses of bool variables can lead to "undefined" behaviours and might look as if it is neither true nor false. For example reading the value of an uninitialized automatic variable or direct

问题 Can someone explain me difference of these? If the program is platform independent doesn't it make it portable too and the opposite? 回答1: Platform independent means, these programs can run in "nearly" all operating systems. Doesn't need to be all, but at least MS, Linux and Mac will be fine to use this word. And, lets dig out the facts behind the word "platform independent". NOTE: The following sentences are my opinions. If anyone read, couldn't understand the logic behind or doesn't like,

问题 At the moment I've got an database with over 100.000 images, they ain't the same size or anything like that but I want to make the following for my compagny: I insert/upload an image and the system returns the image which is most likely the same. I don't know what algorithm to use but it needs to be fast. I can pre-process all the other images and put some info in the database which I use for the comparison. Now what I want to know what the fastest way is to compare the images (with a good

问题 I have the following code snippet: if([]) { console.log("first is true"); } The console says first is true which means [] is true. Now I am wondering why this: if([] == true) { console.log("second is true"); } and this: if([] === true) { console.log("third is true"); } are not true . If the console logged first is true in the first snippet, that means [] should be true, right? So why do the latter two comparisons fail? Here is the fiddle. 回答1: This is by specification. By the ECMAScript 2015

问题 I just learnt about Enums and Types in Ada and decided to write a small program to practice: with Ada.Text_IO; use Ada.Text_IO; with Ada.Integer_Text_IO; use Ada.Integer_Text_IO; procedure Day is type Day_Of_The_Week is (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday); subtype Weekday is Day_Of_The_Week range Monday..Friday; subtype Weekend is Day_Of_The_Week range Saturday..Sunday; function is_Weekday ( dayOfTheWeek: in Day_Of_The_Week) return Boolean is begin if(--?--) end

问题 I was just debugging a script and found that an if-statement wasn't working the way I expected it to. var_dump("6064365413078728979" == "6064365413078728452"); die(); The code above will result in the following: bool(true) With the === operator it works as expected. Anyone got any ideas why? I'm using PHP Version 5.3.13 with a wamp installation on a x64 windows machine. 回答1: <?php $a=6064365413078728979; $b=6064365413078728452; echo $a."<br>".$b; //var_dump( $a==$b ); die(); ?> When you run

问题 I have a simple example application here where I am multiplying and adding double variables and then comparing them against an expected result. In both cases the result is equal to the expected result yet when I do the comparison it fails. static void Main(string[] args) { double a = 98.1; double b = 107.7; double c = 92.5; double d = 96.5; double expectedResult = 88.5; double result1 = (1*2*a) + (-1*1*b); double result2 = (1*2*c) + (-1*1*d); Console.WriteLine(String.Format("2x{0} - {1} = {2}

问题 I got a very awkward and specific issue with a simplexml evaluation. The code: $simplexml = simplexml_load_string($xmlstring); var_dump($simplexml); var_dump($simplexml == false); //this comparison var_dump($simplexml) returns the actual structure of my simplexml but the comparison returns 'true' for this specific simplexml, which I can't show the structure because of my contract. I'm sure that's very specifc issue 'cause I tried other XML strings and the comparison returns 'false'.