SEARCH KEYWORD -- Bit operation


  Will nil == nil be true in GoLang

There is some interview question may ask whether nil == nil be true in GoLang. Wil it be true. false or compilation error? To know the answer, some knowledge about nil in GoLang needs to be explained first. nil definition According to Go's official documentation, the definition of nil is // nil is a predeclared identifier representing the zero value for a // pointer, channel, func, interface, map, or slice type. var nil Type // Type must be a pointer, channel, func, interface, map, or slice type...

   GOLANG,NIL,NIL EXPLANATION     2021-08-08 02:54:15

  The hidden risk of passing slice as function parameter

In Go's source code or other open source libraries, there are lots of cases where a slice pointer is passed to function instead of slice itself. This brings up a doubt why not passing slice directly as its internal is backed by an array pointer to point to underlying data? For example, in log package, the formatHeader function takes a parameter buf as type *[]byte instead of []byte. func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {} Let's understand the r...

   GOLANG,SLICE,SLICE POINTER     2020-12-13 06:11:14

  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

  Special ARP Uses: Gratuitous ARP, ARP Probe, and ARP Announce

In an Ethernet environment, all data is ultimately sent in the form of a Layer 2 Ethernet Frame, which includes the Src MAC, Dst MAC, and other headers such as CRC, etc. Ethernet will then deliver the data to the destination. When we program, we often specify the IP and Port, but rarely specify the MAC address. So, how is the Frame sent out? This is done by the operating system. If the system does not know the MAC address corresponding to an IP, it will send a broadcast ARP request (since this r...

   ARP,NETWORK,LINUX     2024-11-07 20:57:26

  Apache Tomcat Installation and Configuration

When you want to install Apache Tomcat on Windows System. You may find that there are some tricky parts. Next I will elaborate the steps to install and configure Tomcat. If you want to install Tomcat as a service without GUI. You need to download the 32-bit Windows.zip from http://tomcat.apache.org/download-70.cgi. After downloading this zip file. You need to unzip this file to the directory which you want to put this software to. After unzipping, you can go to the bin directory and find t...

   TOMCAT 7,WINDOWS,APACHE,INSTALL,CONFIGUR     2011-04-10 14:17:21

  20 bit operations programmers should know

While talking about bit operation, programmers usually think about its efficiency. In embedded programming and system core optimization, appropriate use of bit operations is always a fascinating. When finding a job, it will help you a lot if you use bit operations when writing codes. Mastering simple bit arithmetic skills is necessary. 1. Get maximum int value int getMaxInt(){           return (1 << 31) - 1;//...

   Bit operation, Tips     2012-12-19 12:53:33

  Three images to understand immutability of String in Java

String is immutable in Java. This means once a String object is created and instantiated, that object cannot be changed. Any operation on the String object will create a new Object instead of operating on the original content. Below are three images to help you understand String immutability in Java. Declare a String String s = "abcd"; s stores the reference to the string content created in the heap. Assign the String reference to another String variable String s2 = s; s2 stores the same ...

   STRING,JAVA     2016-03-11 20:58:28

  How does Base64 work

Base64 is a data encoding scheme used in safe data transfer such as HTTP and its extensions. Base64 encoding can conver arbitrary group of bytes into a sequence of readable ASCII characters. These converted characters can safely put in a HTTP header without causing any problem while the peers process the HTTP header. Base64 encoding was invented as part of the MIME content transfer encoding. It is similar to other encoding schemes such as Uuencode and BinHex but with higher efficiency....

   ALGORITHM,BASE64     2016-03-09 23:47:40

  Tips for improving PHP efficiency

0. Using single quote to replace double quote to enclose string literal, this will be a bit faster. Because PHP engine will search variables in double quoted string. 1. If a method in class can be declared as static, then make it static, this will be 4 times faster. 2. $row["id"] is 7 times faster than $row[id] 3. echo is faster than print, and you should use multiple parameters instead of string concatenation, i.e use comma(,) instead of dot(.) to concatenate string. For example echo $str1,$str...

   PHP, efficiency, tips     2012-10-01 19:39:06

  You know what UTF-8 is when you see it?

When we are coding we may often see some encoding specifications in our source codes such as UTF-8,GB2312. Do you know what these encoding mean and why we need them? In this post, Julián Solórzano will introduce the most widely used encoding specification around the world accomodating all different character sets in the world. UTF-8 is a method for encoding Unicode characters using 8-bit sequences. Unicode is a standard for representing a great variety of characters from many ...

   UTF-8,Encoding     2014-04-18 22:13:44

RECENT