If year is non-negative: Sakamoto algorithm implementation in C++: 0 = sunday, 1 = monday, ..., 6 = saturday. static int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4}; int dow(int y, int m, int d) { y -= m<3; return (d + t[m-1] + y + y/4 - y/100 + y/400) % 7; } In Javascript: // m = 1, 2, ..., 12 // result: 0 = sun, 1 = mon, ..., 6 = sat function dayOfWeek(y, m, d) { if (m<3) y-- m = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4][m-1] return (d + m + y + ~~(y/4) - ~~(y/100) + ~~(y/400)) % 7 }

Try this in your interpreter such as javascript or python: Input: .1 + .2 Output: 0.30000000000000004 Input: .1 + .2 === .3 Output: false Rationale: we (humans) use decimal representation for numbers (the number we write in the console, the number printed out), while internally the interpreters use binary representation which causes

This post comes from the journey when I tried to find a deterministic hash function that maps different natural numbers (for instance, an ID in a database) to different strings with the shortest length possible and an absolute zero possibility of collision. Eventually, I found a perfect answer for this,

Recently Lens disallows the use of its app without an account. The app even hides the close button. Here is how to install a working version 5.4 without an account. Download Lens 5.4 binary from here: https://gateway.pinata.cloud/ipfs/QmVVpMtbecfsyofgKZ2buHM7Xd6Shcr6HFJWNciRLeMPVx And add to /etc/hosts: 127.

Sometimes, your MySQL client faces thsi error: MySQL: ERROR 1040: Too many connections To  get current max connections setting show variables like "%max_connections%"; Result max_connections 151 mysqlx_max_connections 100 Default value is 151. To update value in the current session Note: the value will be reset when

This topic discusses how base64 works, and the usage of the padding and non-alphabet characters. RFC4648 link: https://datatracker.ietf.org/doc/html/rfc4648#section-4 Base64 encodes a binary buffer to ASCII using the following 65 characters for encoding. Table 1: The Base 64 Alphabet Value Encoding Value Encoding Value

Sometimes, you observe that the database servers (postgres, redis, etc.) being disconnected after being idle for a while. This is due to the keepalive config, in which tcp connections are killed if they are detected not being used for a specific time range. This configuration is imposed by numerous components

Yarn 2 gitignore content Default option (non-zero install + node_modules linker) .pnp.* .yarn/* !.yarn/patches !.yarn/plugins !.yarn/releases !.yarn/sdks !.yarn/versions node_modules node_modules entry can be removed unless you are using nodeLinker: node-modules option in .yarnrc.yml. Zero-install option If you have no idea what zero-install

This post shows the best practices to create a hybrid npm package, which supports both commonjs and ES module types. Background CommonJS module: const {myMethod} = require('my-package') ES module: import {myMethod} from 'my-package' How? I will show how to make your package my-package support both types of import. In the

To get stat about system storage sudo du -h --max-depth=1 / 2>/dev/null | sort -h Result: 0 /dev 0 /proc 0 /sys 4.0K /home 4.0K /mnt 4.0K /srv 8.0K /build 12K /media 16K /lost+found 60K /tmp 192K /ephe 2.9M /run 5.8M /etc

To find where the font files are stored in the system, use the following command line fc-list | grep For example: # fc-list | grep '游明朝' /home/transang/.local/share/fonts/Mincho/Yu Mincho Demibold.ttf: Yu Mincho,游明朝,Yu Mincho Demibold,游明朝 Demibold:style=Demibold,Bold /home/transang/.local/share/fonts/Mincho/

In Google Play Console, if you get the following error. This post will show how to solve it. Error This release includes the com.google.android.gms.permission.AD_ID permission but your declaration on Play Console says your app doesn't use advertising ID. You must update your advertising ID

I share several useful javascript/nodejs resources. * Everyday javascript, list of trending javascript projects including short-term trending stuffs: https://bestofjs.org/ * Medium/long-term trending javascript technologies, annual Javascript survey (multiple languages available): https://stateofjs.com/ Its sibling css version (multiple languages available): https://stateofcss.com/ * Learn javascript through efficient code

I list several useful resources for Flutter dev. * Official home page: https://docs.flutter.dev/ * Flutter Layout Cheat Sheet: https://medium.com/flutter-community/flutter-layout-cheat-sheet-5363348d037e, snapshot. * From the same author, Flutter Animation Cheat Sheet: https://medium.com/flutter-community/flutter-animations-cheat-sheet-7f8cebfb850c, snapshot, demo. * Inherited widget in deep (in Japanese, Flutter大学): https://blog.flutteruniv.

iptables rules are all lost when the PC is shutdown. This post shows how to permanently enable the added rules even after restarts. The post uses systemctl startup script introduced here. Suppose that you want to add this rule: -A INPUT -i docker0 -j ACCEPT -p tcp --dport 1234. Step

Sometimes you need to quickly fix an npm package without waiting for a new version to be published which usually takes time. In this post, I will show you how to do that with yarn 2, without using any additional tools. For yarn 1 users, please use the patch-package package

Problem Sometimes, the OS open a new VSCode instance when you want to open a directory (via xdg-open) with the default file manager (such as nautilus). Many users have claimed about this issue: #41037, #80499, #44344, archlinux, ... Background The OS chooses an application when opening a file (directory is a

This post includes the following content: * Create a certificate signing request (CSR) * Create your own certificate authority (CA) certificate to self-sign the CSR * Test the signed certificate with chrome and curl Part 1: Create a certificate signing request (CSR) Step 1: Create a private RSA key openssl genrsa -out server.

In this post, I will show 3 ways to use apt in a private server (a server that does not have direct internet access). Method 1: Download the .deb files and install them manually Adding  --print-uris to the apt command will print the URLs to download necessary .deb files. You

This post shows you how to SSH through a proxy server. Prerequisites The local client is required to have OpenBSD netcat installed. There are 2 versions of netcat. Traditional netcat and OpenBSD netcat. This tutorial explicitly requires OpenBSD netcat. Traditional netcat won't work. See their difference here. In macOS: # nc

Running (training) legacy machine learning models, especially models written for TensorFlow v1, is not a trivial task mostly due to the version incompatibility issue. This post will show the compatibility table with references to official pages. The general flow of the compatibility resolving process is * TensorFlow → Python * TensorFlow → Cudnn/Cuda

Initially, when you create a Kubernetes cluster in AWS (or we call EKS = Elastic Kubernetes Service), only the creator can have full access to the cluster. Other AWS users, even with the Administrator access of the AWS organization, can see the cluster name and several general configurations, but cannot access

You have your own AWS account (in your organization), and several accounts in client organizations. This post shows you how to manage all accesses in a single account. So that you do not have to log out and log in every time. Some values used in this post: * Your organization

For security purposes, some browsers have a minimum font setting larger than zero by default in a specific condition. When your website has text with a font size smaller than 10px or 12px, you should expect that that text might be rendered as 10px (even you set it as smaller,

It sometimes happens that although you have already set up your private/public key, you still cannot get connected to the remote server with ssh. In practice, there is an uncountable number of reasons: firewall, server configuration that restricts external access, ... The recommended method to find the reason is to