syntax

问题 I tried to confirm if a file exists using the following line of code: os.path.isfile() But I noticed if back slash is used by copy&paste from Windows OS: os.path.isfile("C:\Users\xxx\Desktop\xxx") I got a syntax error: (unicode error) etc etc etc. When forward slash is used: os.path.isfile("C:/Users/xxx/Desktop/xxx") It worked. Can I please ask why this happened? Even the answer is as simple as :"It is a convention." 回答1: Backslash is the escape symbol. This should work: os.path.isfile("C:\

问题 I was reading some Rust code and I came across this line if let Some(path) = env::args().nth(1) { Inside of this function fn main() { if let Some(path) = env::args().nth(1) { // Try reading the file provided by the path. let mut file = File::open(path).expect("Failed reading file."); let mut content = String::new(); file.read_to_string(&mut content); perform_conversion(content.as_str()).expect("Conversion failed."); } else { println!( "provide a path to a .cue file to be converted into a

问题 Is there any differences among the following two statements? import os import os as os If so, which one is more preferred? 回答1: The below syntax will help you in understanding the usage of using "as" keyword while importing modules import NAMES as RENAME from MODULE searching HOW Using this helps developer to make use of user specific name for imported modules. Example: import random print random.randint(1,100) Now I would like to introduce user specific module name for random module thus I

问题 Why does $a = GPS AcroRd32 | Measure $a.Count work, when GPS AcroRd32 | Measure -Property Count doesn't? The first example returns a value of 2 , which is what I want, an integer. The second example returns this: Measure-Object : Property "Count" cannot be found in any object(s) input. At line:1 char:23 + GPS AcroRd32 | Measure <<<< -Property Count + CategoryInfo : InvalidArgument: (:) [Measure-Object], PSArgumentException + FullyQualifiedErrorId : GenericMeasurePropertyNotFound,Microsoft

问题 Why does $a = GPS AcroRd32 | Measure $a.Count work, when GPS AcroRd32 | Measure -Property Count doesn't? The first example returns a value of 2 , which is what I want, an integer. The second example returns this: Measure-Object : Property "Count" cannot be found in any object(s) input. At line:1 char:23 + GPS AcroRd32 | Measure <<<< -Property Count + CategoryInfo : InvalidArgument: (:) [Measure-Object], PSArgumentException + FullyQualifiedErrorId : GenericMeasurePropertyNotFound,Microsoft

问题 I'm using a format operator inside a script with a following example: $current = 1 $total = 1250 $userCN = "contoso.com/CONTOSO/Users/Adam Smith" "{0, -35}: {1}" -f "SUCCESS: Updated user $current/$total", $userCN This excpectedly shows the following output: SUCCESS: Updated user 1/1250 : contoso.com/CONTOSO/Users/Adam Smith The format operator is there to keep the targeted output text in place with current / total running numbers varying between 1-99999. Without the format operator I could

问题 I encountered something I've never seen before in C# (at least I don't recognize it anyways)...it's got me feeling pretty dumb at the moment. I downloaded Dapper, which is awesome by the way, and was making my first query with a stored procedure. connection.Query<MyObject>("[dbo].[sp_MyStoredProc]", new { Name = keywords }, commandType: CommandType.StoredProcedure); The intellisense method signature says this should be an IDbTransaction . Is this some type of shorthand that converts:

问题 I am trying to add «€» as an alias for the «$» scalar, and doing it with a Slang is the way to do it I think. But perl6.doc doesn't mention Slangs at all. I have read the following: https://perlgeek.de/en/article/mutable-grammar-for-perl-6 (from 2008) https://mouq.github.io/slangs.html And looked at the Slang::Roman and Slang::Tuxic modules. The result is this file (ScalarEU.pm6): use nqp; unit module ScalarEU2; sub EXPORT(|) { my role Euscalar { token sigil:sym<$> { '€' | '$' } } my Mu $MAIN

问题 I want to create a svelte component that receives the name and path of an image. I want to have the component set the image as the "background-image" using CSS. I've tried the following which does not seem to work... Component called in App.svelte : <Image image_url='./images/image1.jpg' /> Image.Svelte <script> export let image_url; </script> <style> .image{ position:relative; opacity: 0.70; background-position:bottom; background-size: cover; background-repeat: no-repeat; background

问题 I am new to Haskell and this mixture of Infix and Prefix notation is confusing me. What is the difference between an operator like '+' and a function like head? How do I write an operator 'c' which does this 1 c 1 = 2? I found this definition a ! b = True. How does Haskell know that I am defining ! and not a function a? 回答1: In Haskell, to create an operator you must use the following "operator symbols": ! # $ % * + . / < = > ? \ ^ | : - ~ So, for example ($$$) a b = a+b Defines an operator $