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  Can two new objects point to the same memory address in GoLang?

Do you have any idea what the output will be for below GoLang snippet? package main import ( "fmt" ) type obj struct{} func main() { a := &obj{} fmt.Printf("%p\n", a) c := &obj{} fmt.Printf("%p\n", c) fmt.Println(a == c) } Many people would think that a and c are two different object instances which have different memory addresses. Hence a == c will be false. But if you try to run the above program, you would see below output 0x5781c8 0x5781c8 true To get to know the reason wh...

   GO,GOLANG,VARIABLE ESCAPE,ZEROBASE     2019-04-06 01:19:52

  Understand unsafe in GoLang

Before going to understand unsafe package in GoLang, the first thing needs to talk about is the pointer in GoLang. If you have a background of C language, you must know what pointer means and its usage. With pointer, you are free to operate any data at memory level which means you have great power, but this means that you have great responsibility as well. That's why it might be considered unsafe in lots of cases. Take a look at a simple example of doubling an integer. package main import "fmt"...

   GOLANG,UNSAFE,ZERO-COPY     2020-03-14 23:18:00

  When will resizing be triggered in Java HashMap?

HashMap is one of the most frequently used collection types in Java, it stores key-value pairs. Ideally it expects to use hash table which expects the data access time complexity to be O(1), however, due to hash conflicts, in reality, it uses linked list or red-black tree to store data which makes the worst case time complexity to be O(logn).  Although collections are using data structures like arrays and linked lists, unlike arrays, they will dynamically resize when there is not enough spa...

   JAVA,RESIZE,HASHMAP,THRESHOLD     2020-05-02 20:41:19

  Useful git commands in daily work

In a developer's daily work, it is frequent to see lots of commits made. It would be a headache if one cannot use git commands well especially when in cases where some fixes need to be made on existing branches. There are some frequently used command such as git pull, git merge and git push. Apart from these, there are some other practical commands which may be useful for real use cases. This post will try to list some of them. git grep  It will lists all files containing the searched keywo...

   GIT,GIT COMMAND,GIT LOG     2022-05-01 03:17:15

  Some lovely software design quotes

  Every time when I read technical books, I like reading the quote of a famous person at the start of a chapter(if any), usually they are very interesting. Here is a collection of famous quotes. Life’s too short to build something nobody wants – Ash Maurya, Running Lean author Give someone a program, you frustrate them for a day; teach them how to program, you frustrate them for a lifetime. – David Leinweber There are two ways of constructing a software design: One way is...

   Quote,Software design     2012-10-13 09:13:34

  Add compiler argument to build Maven project

Maven is a software project to manage a project's build, reporting and documentation from a central piece of information. It's now widely used t build and deploy projects. It can help automatically maintain the dependencies of projects. There is a central project configuration file named pom.xml. Here you can configure the project you want to build.  In this post, we will show you how to add compiler argument when using javac to compile Java source code. Sometimes we need to pass compi...

   Maven,compiler argument, compiler option, Java 8     2015-04-10 21:59:00

  Use CSS calc to align an element vertically

calc function is a function introduced in CSS3, it can be used to calculate length values. There are a few good features which make it suitable for aligning an element vertically. One good part is that the operands can have different units like percentage, px, rem etc. This makes it very flexible when calculating the length value. One example: .rect{ margin-top:20px; height:50px; background:green; width:calc(100%-20px); } Here the left operand uses percentage while the right one ...

   CSS3,CALC,VERTICAL ALIGN     2019-08-23 20:30:23

  JSON unmarshal in GoLang

In almost all mainstream programming languages, there is either built-in or third-party library to support parse JSON data because it is so popular for organizing and transferring data among different services. In GoLang, the built in json package also provides functions for marshalling and unmarshalling JSON data. Marshalling GoLang struct to a JSON string is relatively simple, just need to call json.Marshal(), it's a bit complicated to unmarshal an arbitrary JSON string into a GoLang struct ob...

   GOLANG,JSON,UNMARSHAL,EMPTY INTERFACE     2019-11-09 21:57:30

  git reset vs git revert

When maintaining code using version control systems such as git, it is unavoidable that we need to rollback some wrong commits either due to bugs or temp code revert. In this case, rookie developers would be very nervous because they may get lost on what they should do to rollback their changes without affecting others, but to veteran developers, this is their routine work and they can show you different ways of doing that. In this post, we will introduce two major ones used frequently by develo...

   GIT,GIT RESET,GIT REVERT     2019-02-02 08:26:39

  Understanding PGO in GoLang 1.20

Background The Go 1.20 version was officially released in February 2023, it introduced the PGO(Profile Guided Optimization) mechanism. The basic principle of PGO can be divided into the following two steps: First, profiling is performed on the program to collect data about the program's runtime and generate a profiling file. When compiling the program, enable the PGO option, and the compiler will optimize the program's performance based on the content in the .pgo file. When compiling a program...

   GO 1.20,PGO,GOLANG     2023-02-28 04:27:46

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