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  Pointers, arrays, and string literals

A recently posted question on Stack Overflow highlighted a common misconception about the role of pointers and arrays held by many programmers learning C.The confusion stems from a misunderstanding concerning the role of pointers and strings in C. A pointer is an address in memory. It often points to an index in an array, such as in the function strtoupper in the following code:void strtoupper(char *str) { if (str) { // null ptr check, courtesy of Michael while (...

   char pointer,initialization,literal,cann     2011-09-22 13:29:23

  A simple tutorial on GoLang connecting to Clickhouse

Go, also known as Golang, is a statically-typed, concurrent programming language created by Google. ClickHouse is a high-performance, column-oriented database management system that can be used for real-time data analysis. This tutorial will provide a deep dive into how to connect to ClickHouse from a Go program, including how to perform common database operations such as SELECT and INSERT statements. Before proceeding, it is assumed that you already have Go and ClickHouse installed on your mach...

   GOLANG,CLICKHOUSE,TUTORIAL     2023-02-11 07:05:36

  Why 0.1+0.2 != 0.3

In programming languages such as JavaScript, c/c++, Java and Matlab, you will find that you will get unexpected result when doing float point calculation. For example, when calculating 0.1 + 0.1, you will not get 0.3: > 0.1 + 0.2 == 0.3 false > 0.1 + 0.2 0.30000000000000004 Don't be surprised of this result, this is the end result of IEEE 754 standard, float point number cannot be accurately represented according to IEEE 754 because: No enough memory is allocated for representing the num...

   float point,comparison,JavaScript     2014-11-19 05:32:46

  Faster than C

Judging the performance of programming languages, usually C is called the leader, though Fortran is often faster. New programming languages commonly use C as their reference and they are really proud to be only so much slower than C. Few language designer try to beat C. What does it take for a language to be faster than C? Better Aliasing Information Aliasing describes the fact that two references might point to the same memory location. For example, consider the canonical memory copy: void...

   C,Performance,Speed,Fortran,Criteria     2012-03-25 09:12:23

  Shell script common interview questions

Shell script is frequently used when monitoring system status on Linux. It's not an easy task to write shell script but it's a very important skill for developers and system administrators to ease work and automate common tasks. This post will share some common interview questions about shell script. 1. Get random characters(8 characters) Method 1 # echo $RANDOM |md5sum |cut -c 1-8 471b94f2 Method 2 # openssl rand -base64 4 vg3BEg== Method 3 # cat /proc/sys/kernel/random/uuid |cut -c 1-8 ed...

   LINUX,INTERVIEW,SHELL SCRIPT     2018-09-28 10:46:00

  JavaScript interview questions

This post will cover the JavaScript questions I have encountered and have seen during my programming career. They will mainly focus on vanilla JavaScript though there are lots of excellent frameworks out there and many people are using them in their daily work. this keyword this keyword is an very important but easy to confuse concept in JavaScript since it is always referring to the calling object of the function. 1. What will be the output of below code snippet? function User(name) { this....

   JAVASCRIPT,ALGORITHM,THIS,CLOSURE     2019-03-09 07:05:46

  How does computer boot up?

The whole boot process of computer can be summarized in 4 phases. 1. BIOS In the 70's  read-only memory(ROM) was invented. The boot program is written into ROM, the first thing the computer does is to read and execute this program when it's powered on. The program in this chip is called "Basic Input/Output System" (BIOS). 1.1 Power-On Self-Test The BIOS will first check whether the computer hardware can fulfill the basic conditions for booting up, this process is called Power-On Self-Test...

   Computer, boot, partition     2013-02-23 23:19:47

  Will tablet revolution really come soon?

The famous Silicon Valley entrepreneur and academic Vivek Wadhwa said a few months ago that tablet revolution would come only if the price dropped below $100. According to The Wall Street Journal, the 4th largest PC manufacturer Acer seems to be the first one to eat crab. It plans to promote $88 Android tablet Acer Iconia B1. Does this indicate that the tablet revolution is coming? According to a person who knows the Acer tablet project, Acer Iconia B1 configuration will be similar to those of ...

   Acer,Tablet,Low price,Tablet revolution     2012-12-24 20:51:33

  Optimization Tricks used by the Lockless Memory Allocator

With the releasing of the Lockless Memory Allocator under the GPL version 3.0 license, we can now discuss more of the optimization tricks used inside it. Many of these are things you wouldn't want to use in normal code. However, when speed is the ultimate goal, sometimes we need to break a few rules and use code that is a little sneaky.The SlabA slab is a well-known technique for allocating fixed size objects. For a given object size, a chunk of memory is divided up into smaller regions of that ...

   Optimization,Memory allocation     2011-11-16 08:02:16

  Today in history : Steve Wozniak invented Apple I in 1975

The original Apple Computer, also known retroactively as the Apple I, or Apple-1, is a personal computer invented by Steve Wozniak ion 29th June, 1975. Wozniak's friend Steve Jobs had the idea of selling the computer. Features:CPU : MCStek 6502CPU Speed : 1MHzBus Speed : 1MHzMemory : 8KbResolution : 60.05 Hz, 40*24 charactersPower : 58WPrice : $666.66The Apple I went on sale in July 1976 at a price of US$666.66, because Wozniak "liked repeating digits" and because they originally sold it to a lo...

   Apple I,History,Steve Wozniak     2012-06-29 06:00:08

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