Concurrency ideologies of Programming Languages: Java, C#, C, C+, Go, and Rust

How fast is doing a go func() for a block of code ?

<p>Is there a performance hit from starting goroutines like this ? Is there a comparable Thread executor (in Java) i.e. goroutine executor ?</p> <hr/>**评论：**<br/><br/>tylermumford: <pre><blockquote> <p>Is there a performance hit from starting goroutines like this ?</p> </blockquote> <p&...阅读全文

Go语言Hello world(GOPATH和Go Module版)

本文是「vangoleo的Go语言学习笔记」系列文章之一。官网: http://www.vangoleo.com/go/go-hello-world-02/ 往期回顾: Go语言入门-你好，Go语言 Go语言入门-Hello World(Go Playground版) 上一篇文章Go语言入门：Hello world中，我们在Golang Playground中体验了Go语言，编写并运行了一个简单的Hello World，相信大家对Go语言的语法有了一些了解。 学习一种编程语言，除了基本的语法，更重要的是要了解如何在实际的工程中使用它。本文中，我会和大家一起，从零开始，安装Go语言，配置环境，安装IDE，开发一个Hello World程序。这个Hello World版我会编写两个版本：GOPA...阅读全文

Job in Sydney: Fullstack Go Web Developer

<p>Digital reputation based start-up in Sydney Australia, is ready to take on the world! We need a third full-stack Senior Go Web Developer.</p> <p>Our ideal candidate will have proven full-stack Go development and also be comfortable in SQL (Postgres) and Ruby on Rails. Experience in PHP, NodeJS or Python is an advantage.</p&...阅读全文

Going to write my webapp in Go instead of Node. Is it a good choice?

<p>I&#39;m a front-end developer but I have coded with a few other languages. Did some PHP projects in the past (with laravel), created a desktop app with Java and I use a bit of C in college. Also did a website with ruby and rails.</p> <p>I&#39;ve been working only with javascript for a couple years at least in the front...阅读全文

240.搜索二维矩阵 II

题目描述 编写一个高效的算法来搜索 m x n 矩阵 matrix 中的一个目标值 target。该矩阵具有以下特性： 每行的元素从左到右升序排列。 每列的元素从上到下升序排列。 示例： 现有矩阵 matrix 如下： [ [1, 4, 7, 11, 15], [2, 5, 8, 12, 19], [3, 6, 9, 16, 22], [10, 13, 14, 17, 24], [18, 21, 23, 26, 30] ] 给定 target = 5，返回 true。 给定 target = 20，返回 false。 思路 1.根据此二维矩阵给出的性质，可以从二维数组的右上角开始搜索，若target大于当前元素，我们的检索方向就向下，若小于，我们的检索方向就向左，若检索出界，还没找到结果，直...阅读全文

duck typing

像鸭子走路，像鸭子叫，那么就是鸭子 描述事物外部行为而非内部结构 严格说go属于结构化类型系统，类似duck typing python c++ 中duck typing （只要retriever 具有get方法即可）但是编译运行才知道错误 def download(retriever r): r.get("www.baidu.com") java 中传入参数必须要实现某个接口，不是duck typing 接口定义 download (使用者) retriever(使用者) golang中接口由使用者定义 typpe assertion n, p := reader.Shape() point := p.(*shp.Point) x := point.X y := point.Y 接口变量里...阅读全文

Using maps, pointers and arrays

<p>Hi guys. I&#39;ve hit bit of a &#34;how should this be done in golang&#34; wall. </p> <p>What I have is a <code>items := map[string][]*someType</code> </p> <p>and a little later a check </p> <pre><code>Add item i if key exists i := new(someType) if cache, ok := items[&...阅读全文

How is no semicolon achieved in GO language(grammar speciifcally)?

<p>Ok so i know go automatically inserts a semicolon if the last token in a input line is an identifier,a basic literal such as a number or string constant, or one of the tokens : break continue fallthrough return ++ -- ) }. Is this implemented in lexers grammar or parsers grammar?(i know lexer breaks the input into tokens). I want to see the...阅读全文

polymorphism madness

<p>I wanted to post this to <a href="/r/programming" rel="nofollow">/r/programming</a> but they only accept links, and I could care less about blogging.</p> <p>First, a short preface. I write a lot of Go code. Not all of it is public and yet very little of it is paid for. Frankly, a number of my hobbie...阅读全文

Is Go 2 actually happening? If so, when will development start?

<hr/>**评论：**<br/><br/>lstokeworth: <pre><p>Go 2 is <a href="http://www.thedynamiccommunicator.com/increase-meeting-productivity-the-idea-parking-lot/">an idea parking lot</a>. There are no plans to start development on Go 2.</p></pre>thockin: <pre><p>It does sort of kill me ...阅读全文

Safe to share data between goroutines without explicit locks?

<p>If I want to share a big tree data structure between goroutines, what happens if two gophers try to reassign a pointer at the same time? Append to a slice? Should I always protect these mutations with explicit locks, or are some operations safe?</p> <p>Does Go at least protect against corruption, in the case of bit-level write...阅读全文

Is Go suitable for building payment gateway backend?

<p>I have seen Java, .net technologies are used in this field. But never heard of Go. I want to know what kind of advantages and drawbacks may be? </p> <hr/>**评论：**<br/><br/>dlsniper: <pre><p>Considering there&#39;s a bank, Monzo in UK, building their whole backend in Go, then yes, Go probably is ok.&l...阅读全文

The creator of node stopped building the language because he knew go was better.

<p><a href="http://pca.st/lT7W">http://pca.st/lT7W</a></p> <hr/>**评论：**<br/><br/>Fwippy: <pre><p>Node isn&#39;t a language.</p></pre>evilmaus: <pre><p>But it is an attempt to bring JavaScript out of the browser.</p></pre>tonymonmaster: <pre>&...阅读全文

Generics: specific use cases

<p>There&#39;s been a <a href="https://www.reddit.com/r/golang/comments/6n2g8w/go2_is_real/">lot</a> <a href="https://www.reddit.com/r/golang/comments/6n31hj/toward_go_2/">of</a> <a href="https://www.reddit.com/r/golang/comments/6na5sy/it_came_to_them_with_a_message/">discussion</a&...阅读全文

Why Go is so popular for web-development?

<p>Hello, guys. I&#39;ve noticed a lot of people switch from traditional web stack to Go. What&#39;s the main purpose?</p> <p>There are several advantages if you think of Go <strong>as a reasonable replacement for C++ or Java.</strong> But Go also seems to have a growing popularity <strong>in web-develop...阅读全文

why is golang interface internally an int

<p>This is totally different from java. I&#39;ve read many articles, but seems like none of them dealing with the design purpose. Is there a TL;DR version of why is this?</p> <hr/>**评论：**<br/><br/>Sythe2o0: <pre><p>Where did you get the impression that an interface was an int? As a datatype, an interfa...阅读全文

JAVA多线程使用场景和注意事项简版

我曾经对自己的小弟说，如果你实在搞不清楚什么时候用HashMap，什么时候用ConcurrentHashMap，那么就用后者，你的代码bug会很少。 他问我：ConcurrentHashMap是什么? -.- 编程不是炫技。大多数情况下，怎么把代码写简单，才是能力。 多线程生来就是复杂的，也是容易出错的。一些难以理解的概念，要规避。本文不讲基础知识，因为你手里就有jdk的源码。 线程 Thread 第一类就是Thread类。大家都知道有两种实现方式。第一可以继承Thread覆盖它的run方法;第二种是实现Runnable接口，实现它的run方法;而第三种创建线程的方法，就是通过线程池。 我们的具体代码实现，就放在run方法中。 我们关注两种情况。一个是线程退出条件，一个是异常处理情况。 线程...阅读全文

构建乘积数组

题目描述 给定一个数组 A[0,1,…,n-1]，请构建一个数组 B[0,1,…,n-1]，其中 B 中的元素 B[i]=A[0]×A[1]×…×A[i-1]×A[i+1]×…×A[n-1]。不能使用除法。 示例 输入: [1,2,3,4,5] 输出: [120,60,40,30,24] 思路 1.可以从题目给出的公式中，推导出一幅图。 根据图片的内容，可以通过计算“三角形”的结果，推导出最终元素的结果。 3.三角形主要包括，上半部和下半部，具体计算详情，可以参看代码。 Java代码实现 class Solution { public int[] constructArr(int[] a) { if(a.length == 0){ return a; } int[] res = new in...阅读全文

Learning the core Go libraries

<p>Hello! I&#39;m new to Golang and this subreddit. I have been learning the basic Go syntax and structure recently, and since I have found it rather intuitive, I&#39;ve decided to take the plunge and truly try and learn as much Go as I can this summer (aka, you&#39;ll probably see me more often in this sub in the future...). I ca...阅读全文

Is interface{} acceptable? Discuss.

<p>If it&#39;s not and sacrificing type safety, then why is it there? If it&#39;s there, why using it is considered bad.? Isn&#39;t it just like an &#34;any&#34; type in many languages (except there is a <code>nil</code> in Go). I&#39;ve heard arguments about this being a bad practices only from the communi...阅读全文

Why golang refuse to provide goroutine id, then they hack their own way to do it?

<p>This is aweful: <a href="https://github.com/golang/net/blob/master/http2/gotrack.go#L51">https://github.com/golang/net/blob/master/http2/gotrack.go#L51</a></p> <p>Ary they enjoying this?</p> <hr/>**评论：**<br/><br/>kodablah: <pre><p>A madlib: Why golang refuse to provide &a...阅读全文

Logging per category like log4j

<p>Hi there, I have been searching a lot, but I haven&#39;t found any logging library that allows me to set different logging levels for different packages. I mean. For example, I want to set my program level to debug, as I develop it, but perhaps, I would also want to a library/package that I use, that of course would use the same loggin...阅读全文

Problem parsing xml file

<p>I have the following xml file: &lt;?xml version=&#34;1.0&#34; encoding=&#34;utf-8&#34; standalone=&#34;yes&#34; ?&gt;</p> <pre><code>&lt;java-update-map version=&#34;1.0&#34;&gt; &lt;mapping&gt; &lt;version&gt;1.8.0_51&lt;/version&gt; ...阅读全文

How do you practice good design?

<p>Hey there,</p> <p>I am aware that this is probably not the 100 percent correct subreddit for this question but since I am currently working mostly with go and also since my current goal is to improve my design of Go programs I wanted to start here.</p> <p>So I was watching this wonderful talk <a href="https...阅读全文

I'm confused, how do generics work in Go ?

<p>I haven&#39;t found much tutorials about generic Go programming, could you guys explain for me how that works ?</p> <hr/>**评论：**<br/><br/>jlund3: <pre><p>My first gut reaction was: Go doesn&#39;t have generics. We use interfaces for generic algorithms and type assertion/reflection for generic dat...阅读全文

老虞学GoLang笔记-常量

开发十年，就只剩下这套Java开发体系了 >>> 常量 常量和C#中的概念相同，在编译期被创建。因为在编译期必须确定其值，因此在声明常量时有一些限制。 其类型必须是：数值、字符串、布尔值 表达式必须是在编译期可计算的 声明常量的同时必须进行初始化，其值不可再次修改 Doc http://golang.org/doc/go_spec.html#Constants http://golang.org/doc/go_spec.html#Constant_expressions http://golang.org/doc/go_spec.html#Constant_declarations http://golang.org//doc/go_spec.html#Iota 语法 const关键字用于声...阅读全文

2019.01.27

内建变量类型 内置变量类型bool, string(u)int, (u)int8, (u)int16, (u)int32, (u)int64, uintptrbyte, runefloat32, float64, complex64, complex128(u)是unsigned代编有符号或无符号go与其他不同的类型1、uintptr go语言的指针类型2、rune 其实rune是char类型，而且是char32位3、complex 复数类型。Go语言类型转化func triangle() { var a ,b int = 3,4 var c int //go语言没有隐式强制类型转换，必须显示强制类型转换 c = int(math.Sqrt(float64(a*a+b*b))) fmt.Pr...阅读全文

利用golang优雅的实现单实例

平时编写代码过程中，经常会遇到对于全局角度只需运行一次的代码，比如全局初始化操作，设计模式中的单例模式。针对单例模式，java中又出现了饿汉模式、懒汉模式，再配合synchronized同步关键字来实现。其目的无非就是将对象只初始化一次，而且最好保证在用到的时候再进行初始化，以避免初始化太早浪费资源，或者两次初始化破坏单例模式的实例唯一性。 Go语言的sync包中提供了一个Once类型来保证全局的唯一性操作，其通过Do(f func())方法来实现，即使 f 函数发生变化，其也不会被执行，下面我们来看一个小例子： package main import ( "fmt" "sync" "time" ) var once sync.Once func main() { //once循环调用fir...阅读全文

is Go good choice as first programming language?

<hr/>**评论：**<br/><br/>sh41: <pre><p>I personally think it&#39;s one of the best programming languages to start with. I wish I could&#39;ve started with it first. The only thing it won&#39;t teach you is frustration of using other less pleasant languages, so you might not have enough context to appreciate so...阅读全文

Question about interfaces

<p>Hey guys<br/> coming from a java world I try to grasp the concepts of go&#39;s interfaces. As far as I understood, the interfaces are implemented implicitly if all methods are satisfied. But isn&#39;t one of the ideas behind interfaces to force the implementation? Like when I have a huge&#39;ish interface and I miss to im...阅读全文

naive "generics" proposals

<p>I work daily in Java (sad, but true), and appreciate there are some cases where generics are really handy. Most examples, to my eye, are sinful. Here are a couple sinful examples:</p> <pre><code>Map&lt;String, List&lt;Map&lt;String, String&gt;&gt;&gt; public class FiniteStateMachine&lt;S exten...阅读全文

树的子结构

题目描述 输入两棵二叉树A，B，判断B是不是A的子结构。（ps：我们约定空树不是任意一个树的子结构） 思路 1.递归比较两个数的结构。 2.比较A树和B树当前的结点，若A树和B树的值相等，则继续比较它们的左右子树；若不相等，则拿A树的左子树和右子树进行同样的过程。 3.当B树遍历到了空结点，说明B是A的子结构；否则不是A的子结构。 Java代码实现 public boolean HasSubtree(TreeNode root1,TreeNode root2) { if(root1 == null || root2 == null){ return false; } boolean flag = judge(root1,root2); if(!flag){ flag = HasSubtree...阅读全文

二叉树的镜像

题目描述 操作给定的二叉树，将其变换为源二叉树的镜像。 输入描述 二叉树的镜像定义：源二叉树 8 / \ 6 10 / \ / \ 5 7 9 11 镜像二叉树 8 / \ 10 6 / \ / \ 11 9 7 5 思路 使用递归算法求解。 如果传入的结点不为null，则将其左右孩子进行交换，然后递归处理其左右孩子即可。 Java代码实现 public class Solution { public void Mirror(TreeNode root) { if(root != null){ TreeNode temp = root.left; root.left = root.right; root.right = temp; Mirror(root.left); Mirror(root...阅读全文

Error handling with streaming data

<p>I&#39;m working on a personal project with Go, and I&#39;m relatively new to it. Part of what I&#39;m doing involves repeatedly reading data out of a Reader in 2-8 byte chunks. The Go way of handling errors (as far as I&#39;ve found) is to use a pattern like this:</p> <pre><code>content := make([]byte, le...阅读全文

AWS Lambda to Fully Support Go

<p>Just announced at re:Invent, Go becomes a first class citizen on Lambda.</p> <hr/>**评论：**<br/><br/>emostafa: <pre><p>Do you guys find it weird that Google Cloud Functions doesn&#39;t support Go ? only nodejs at the moment.</p></pre>chuyskywalker: <pre><p>GCF is really behind o...阅读全文

How can Go make you a master of web development

<p>I have been developing applications in Go for a year now, and I really want to thank Google and the community to make such a great language and countless useful modules. I have learned so much and I would like to share what I have learned so far.</p> <p><a href="https://medium.com/@houyubing24/how-can-go-make-you-a-mast...阅读全文

What's a good project to do to learn Go?

<p>I have some downtime at work and I can spend my time learning what I want. Go has been on the list for a while and I&#39;d really like to learn it and possibly use it in real projects.</p> <p>Now, I could make a web backend with an MVC architecture, make some endpoints etc... But that&#39;s kinda boring as it would jus...阅读全文

Go web developer jobs?

<p>I&#39;m a 15 year old that&#39;s currently learning Go. I love it. Seriously, so much better than Node and Java for me. The thing is, when I look for jobs (well really I&#39;d be looking for an internship), I have like 5 results for Go, and hundreds for Java, JavaScript, etc. My question is this: is Go a language that you can m...阅读全文

Preferred Golang alternatives to traditional object-oriented patterns?

<p>A lot of programming teaching material these days assumes that you are using a traditional object-oriented language (example: Java) with traditional object-oriented patterns (example: inheritance) to structure and model your program. In the case of Go, it is a different language with different building blocks. Then, what are the preferred ...阅读全文

Decisions around usage of nil in go?

<p>I have been using go for quite awhile, and haven&#39;t really given much thought to the way that the usage of nil is used versus other languages I have used (Java/C#/Node). I have always kind of accepted it for what it was.</p> <p>However, as golang makes more of an appearance in our stack, I find myself questioning why th...阅读全文

golang concurrency with real life examples

<p>Goroutine works like the thread in java or any other multi-threading programming language, though the internal concept is different. Goroutine is more lightweight than processor thread. It takes little memory (on average 4~8 KB) than regular thread. Goroutines are managed by thread manager in runtime.</p> <p><a href="ht...阅读全文

Android Development?

<p>I am brand new to golang. I am enjoying everything I have learned about it so far. However I cant seem to find a clear answer on whether this is a legitimate way to design Android Apps or if I should stick to Java for this. I see alot of posts about how it&#39;s coming, but a lot of them are from like 2 years ago. Anyone here use golan...阅读全文

What is the proper way of throwing errors in go code?

<p>So I was making a function that interfaces with a database and has errors implemented like this:</p> <pre><code> // A function to create a new post func CreatePost(title string, content string) (error) { // Open a db connection and check errors db, dbErr := InitDb() defer db.Close() if dbErr != nil { ...阅读全文

Best site or place to start Golang

<p>Hey, I was wondering if any of you know what are some of the best sites or places to start learning Golang, thanks.</p> <hr/>**评论：**<br/><br/>gobdgobd: <pre><p>The tour of go is great!</p> <p><a href="https://tour.golang.org/welcome/1" rel="nofollow">https://tour.golang....阅读全文

[noobish question] struct pointers?

<p>Hi everyone!<br/> noob question here as I&#39;m taking the Go tour on the website. My main languages are Python and Java (although I know a bit of Rust).<br/> Now, I understand how to use pointers, but as I was going through the pointers section of the tour I was wondering:<br/> if we can initialize structs this way ...阅读全文

Thinking about using Go as a composite service.

<p>I have a composite service aggregating data from other microservices, I was wondering how go would handle thousands of aggregations.</p> <hr/>**评论：**<br/><br/>xy8_t_rel_: <pre><p>define composite service.</p></pre>lolomfgkthxbai: <pre><p>Is that the buzzword of the year? Composite...阅读全文

老虞学GoLang笔记-常量

开发十年，就只剩下这套Java开发体系了 >>> 常量 常量和C#中的概念相同，在编译期被创建。因为在编译期必须确定其值，因此在声明常量时有一些限制。 其类型必须是：数值、字符串、布尔值 表达式必须是在编译期可计算的 声明常量的同时必须进行初始化，其值不可再次修改 Doc http://golang.org/doc/go_spec.html#Constants http://golang.org/doc/go_spec.html#Constant_expressions http://golang.org/doc/go_spec.html#Constant_declarations http://golang.org//doc/go_spec.html#Iota 语法 const关键字用于声...阅读全文

Go语言入门：Hello world

本文是「vangoleo的Go语言学习笔记」系列文章之一。官网: http://www.vangoleo.com/go/go-hello-world/ 在上一篇文章你好，Go语言中，我们对Go语言的历史和特点有了认识。接下来，我们就正式进入Go的学习了。按照大部分编程语言的惯例，我们以经典的“Hello World”开始Go语言的学习之旅。 经典的“Hello World”案例来自于1978年出版的C语言圣经。很巧合的是该书的作者Brian W. Kernighan也是《Go语言圣经》一书的作者。 本教程中，我会使用最方便的方式Golang Playground来体验Go语言。在浏览器中打开https://play.golang.org...阅读全文

leetcode_55

Golang: 思路：这题挺有意思的，但并不是在于它的难度上，还是解题的思路上。目前我实现的是思路一：从前往后对数组做处理，但实现的效率极低，大概时间复杂度15%，空间复杂度15%左右。所以更高效的应该是思路二：使用迭代去实现一种类似回溯的方法，对数组进行从后往前的处理。后面我实现了思路二，程序效率如下： 实现效果 下面着重讲下思路二，这里有个前提，即这个问题是可以分解成子问题的。举例分析，我们从arr[i]可以到达终点，那么能否到达终点这个问题就变成了能否到达arr[i]这个问题了。当一个问题可以被分解，那么迭代就有了可行性。 Emmm，对于陌生的题，我会先选择最熟悉的JAVA去写，后面才会用Go去复写，所以上面的提交图是JAVA的。下面给出Go语言实现的代码： func canJump(...阅读全文