投稿時間:2021-05-12 00:40:39 RSSフィード2021-05-12 00:00 分まとめ(49件)

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AWS	AWS	How do I copy an Amazon Redshift cluster to a different AWS account?	https://www.youtube.com/watch?v=AGNSabpaOec	How do I copy an Amazon Redshift cluster to a different AWS account Skip directly to the demo For more details see the Knowledge Center article with this video Joao shows you how to copy an Amazon Redshift cluster to a different AWS account	2021-05-11 14:56:01
AWS	lambdaタグが付けられた新着投稿 - Qiita	AWS Cognitoでユーザー情報をAWS Lambda(Golang)から取得する方法	https://qiita.com/tenshinhan_yamucha/items/7df880c15e5f7ab72117	まず、apiGWEventRequestContextAuthorizerclaimsを型アサーションでmapstringinterface型にして、mapのキーを取り出すという感じです。	2021-05-11 23:09:57
python	Pythonタグが付けられた新着投稿 - Qiita	Serverless Frameworkで環境変数を扱いたい	https://qiita.com/ktoyod/items/2b071c1877d51b24cac4	ServerlessFrameworkで環境変数を扱いたい背景ServerlessFrameworkを使っていて秘匿情報どうしようって悩んだときに、公式でサポートされていたのでその設定方法を書く。	2021-05-11 23:32:57
python	Pythonタグが付けられた新着投稿 - Qiita	Python boot camp by Dr.Angela day13	https://qiita.com/Shellyhackinglab/items/1bfb1f62b32d22a807e9	range開始数終了数という書き方で、rangeと書くことで添え字indexが番から番までの個のオブジェクトを生成するので、iになることはありえないため、printされない。	2021-05-11 23:04:05
js	JavaScriptタグが付けられた新着投稿 - Qiita	【Javascript】clip-pathでスライドアニメーションを作ってみた	https://qiita.com/redrabbit1104/items/7de0aa39772e0bb67c4e	また、clippathをslidemainimages要素に指定します。	2021-05-11 23:58:34
js	JavaScriptタグが付けられた新着投稿 - Qiita	【JavaScript】テキストボックスに「リンク名」と「URL」を入力しボタンをクリックすると、入力されたリンク名とリンク先URLが設定されたa要素を追加するプログラムを作成	https://qiita.com/panda-chibi/items/7cf4ba5126438b51a35c		2021-05-11 23:06:10
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	JavaScriptの関数、引数、戻り値の理解を深めたい	https://teratail.com/questions/337780?rss=all	JavaScriptの関数、引数、戻り値の理解を深めたい関数Aに引数で当てはめた値を戻り値で出力したいです。	2021-05-12 00:00:10
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	RailsアプリでReactが立ち上がらない。	https://teratail.com/questions/337779?rss=all	RailsアプリでReactが立ち上がらない。	2021-05-11 23:58:23
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	vue の this.xxx が空になってしまいます	https://teratail.com/questions/337778?rss=all	下記のコードの「consolelogthismarkers」を確認すると結果が「Array」になってしまいます。	2021-05-11 23:51:58
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	ログイン情報を保持したまま次のページに遷移したい	https://teratail.com/questions/337777?rss=all	コードはこのように書きました。	2021-05-11 23:41:35
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	Python 乱数生成器について	https://teratail.com/questions/337776?rss=all	Xを適当な以上の整数とし、XXXを次の漸化式で求めます。	2021-05-11 23:04:17
AWS	AWSタグが付けられた新着投稿 - Qiita	AWS DeepRacerにカジュアル参加してみました	https://qiita.com/seigot/items/88f820f1e6431f0753c3	今回は以下を設定しました。	2021-05-11 23:47:22
AWS	AWSタグが付けられた新着投稿 - Qiita	【コピペ】AWS Cloud9でLaravel環境を構築その壱	https://qiita.com/_bobtabo_/items/9fc5a4d35ec1b5bfeaf4	マシンスペックMacminimacOSCatalinaxIntelCoreiGHzコアメモリGBSSDGBLaravel環境Nginx最新版PHPPHPFPMxMySQLComposer最新版LaravelやることCloudでLaravel環境構築ミドルウェア達は手動構築AWSCloudの準備下記を参考に準備する。	2021-05-11 23:15:46
AWS	AWSタグが付けられた新着投稿 - Qiita	AWS Cognitoでユーザー情報をAWS Lambda(Golang)から取得する方法	https://qiita.com/tenshinhan_yamucha/items/7df880c15e5f7ab72117	まず、apiGWEventRequestContextAuthorizerclaimsを型アサーションでmapstringinterface型にして、mapのキーを取り出すという感じです。	2021-05-11 23:09:57
Docker	dockerタグが付けられた新着投稿 - Qiita	NginxをProxyサーバとして動かす	https://qiita.com/neo_fukafukafukka/items/8667e461d2208e0bb295	dockerexecithttpdserverbinbashyumyinstallhttpdNginxのProxyとしての設定各コンテナのIPだけ調べておく。	2021-05-11 23:53:32
golang	Goタグが付けられた新着投稿 - Qiita	AWS Cognitoでユーザー情報をAWS Lambda(Golang)から取得する方法	https://qiita.com/tenshinhan_yamucha/items/7df880c15e5f7ab72117	まず、apiGWEventRequestContextAuthorizerclaimsを型アサーションでmapstringinterface型にして、mapのキーを取り出すという感じです。	2021-05-11 23:09:57
Linux	CentOSタグが付けられた新着投稿 - Qiita	NginxをProxyサーバとして動かす	https://qiita.com/neo_fukafukafukka/items/8667e461d2208e0bb295	dockerexecithttpdserverbinbashyumyinstallhttpdNginxのProxyとしての設定各コンテナのIPだけ調べておく。	2021-05-11 23:53:32
Linux	CentOSタグが付けられた新着投稿 - Qiita	OSSのSquidを使ってProxyサーバを立ててみる	https://qiita.com/neo_fukafukafukka/items/baf12cb012a0f6f6998b	systemctlisenabledfirewalldenabledfirewalldに、squidのポート番号である番だけ開けるfirewallcmdaddporttcpsuccessfirewallcmdlistportstcpBASIC認証の設定一応、proxyサーバー上でsquidの設定により、BASIC認証もできるみたいなので真似てみた。	2021-05-11 23:02:34
Git	Gitタグが付けられた新着投稿 - Qiita	GitHubでのマージの種類	https://qiita.com/YotaHamasaki/items/f907d9fe687002199cb2	これは別々のブランチでそれぞれが開発している時に、別ブランチの変更内容を自分のブランチに取り込むマージとなります。	2021-05-11 23:35:32
技術ブログ	Developers.IO	AWS Amplify の Admin Queries API にユーザーを作成・更新・削除する機能が提供されていないので追加してみた	https://dev.classmethod.jp/articles/amplify-admin-queries-api-custom/	adminqueriesapi	2021-05-11 14:34:52
技術ブログ	Developers.IO	BigQueryでPreviewになったPIVOTとUNPIVOTを試す	https://dev.classmethod.jp/articles/bq-new-pivot/	releasenotes	2021-05-11 14:27:08
海外TECH	DEV Community	Amazing Image Slider Using Flickity & JS	https://dev.to/nikhil27b/image-slider-using-flickity-js-4g8h	Amazing Image Slider Using Flickity amp JSToday I created a simple Image Slider Using Flickity amp JS In this image slider I use flickity and some jquery also to animate the slider I hope you like this also comments about your thoughts For more content follow me on Instagram developer nikhil Thank you	2021-05-11 14:17:04
海外TECH	DEV Community	JavaScript Project Ideas	https://dev.to/mrdanishsaleem/javascript-project-ideas-3og8	JavaScript Project Ideas Quiz ApplicationChoose a topic that interests you and create a dynamic quiz using JavaScript Keep track of the users score and notify them which answers are correct As an added challenge add a timer to each question Form ValidationCreate a user input form that ensures that users are correctly filling in inputs with correct types and restraints Form validation is common in front end development and necessary to mitigate security risks Add CSS classes that turn the input red on incorrect submission Tetris GameUsing HTML canvas and JavaScript you can create a fun interactive game JavaScript can be used to create fully fledged games in the browser or an external game engine platforms Be sure to check out external D and D libraries to integrate with your project JavaScript ClockLearning how to work with time in JavaScript is important First display the current time in your current location Then allow the user to change time zones Checkout MomentJS library when working with displaying dates and times Chat ApplicationThis project gives you the opportunity to work on both front end and back end skills This project also requires you learn about websockets for real time connection MP PlayerLearn to interact with audio files using JavaScript Build out the UI to play pause stop and restart and audio recording Once you ve learn to create your own MP player look into libraries such as AmplitudeJs and APlayer to avoid rolling your own JavaScript AnimationJavaScript has a variety of animation libraries that are definitely worth exploring In fact all of the previous projects can incorporate some animations	2021-05-11 14:04:19
海外TECH	DEV Community	DB max connection limits for Rails app and Postgres, Redis, Puma settings	https://dev.to/arturt/db-max-connection-limits-for-rails-app-and-postgres-redis-puma-settings-427h	DB max connection limits for Rails app and Postgres Redis Puma settingsConfiguring the database connections pool for the Rails app might not be a straightforward task for many programmers There is a constraint of max opened connections on a database level Your server environment configuration can change in time and affect the number of connections to the database required For instance number of servers you use can change when you autoscale it based on the web traffic It means that the number of web processes threads running for Puma or Unicorn servers could change All this adds additional complexity When you use two databases e g Postgres Redis everything gets more complex In this article we will address that You will learn how to estimate needed database connections for your Ruby on Rails production application Why do available database connections matter The first question is why do you need to care about available database connections The answer is simple Suppose you configured your Ruby application to open too many DB connections In that case it could happen that you will get ActiveRecord ConnectionTimeoutError exceptions from the application when the database cannot handle more new connections from your Rails app It can result in errors visible for your web app users This problem might not be apparent immediately Often you will find out about it in production Your application might work just fine until specific circumstances cause the Rails app to need more DB connections which can trigger exception flood Let s see how to avoid it RoR application configuration step by stepLet s break a typical Ruby on Rails application down into smaller components that use databases We have a Rails application that uses the Postgres database for ActiveRecord usage We also use the Redis database for background workers like Sidekiq It looks simple isn t it Let s start with that and later on we will add more complexity to the mix Postgres database connections how to check the limit How to check how many available connections do you have for Postgres If you use a dedicated server with Postgres installed then most likely you have a default max connections which is typically connections If you use a Postgres instance on the AWS then you need to check the AWS documentation to find out what s the max allowed connections to your database instance it depends on if you use Amazon RDS or Aurora and what is server instance class If you use Heroku you can check the Connection Limit for the Postgres Heroku add on to check max acceptable connections ActiveRecord connection poolIn your Rails application the config database yml file contains the pool option As explained in the Rails docs Active Record database connections are managed by ActiveRecord ConnectionAdapters ConnectionPool which ensures that a connection pool synchronizes the amount of thread access to a limited number of database connections Since the connection pooling is handled inside of Active Record by default all application servers Thin Puma Unicorn etc should behave the same The database connection pool is initially empty As demand for connections increases it will create them until it reaches the connection pool limit Any one request will check out a connection the first time it requires access to the database At the end of the request it will check the connection back in This means that the additional connection slot will be available again for the next request in the queue The pool can be defined this way production adapter postgresql database blog production pool or as a part of a URL to the database development url postgresql localhost blog production pool The URL option is popular when you host a database on an external server like Amazon RDS Then you could define the URL this way production url postgres blog production PASSWORD blog production abcdefgh eu west rds amazonaws com blog production sslca config rds combined ca bundle pem amp pool Please note that for the production you should not commit credentials in the config database yml file Instead store it in environment variables and then read the value at your Rails app s runtime production url lt ENV DB URL gt How does ActiveRecord connection pool affects Postgres max connections Let s start with a simple example Your application may use one of the application servers like Puma or Unicorn Let s focus on Puma because it s more complex as it has a separate configuration for several processes known as workers in Puma terms and threads Unicorn runs in a single thread only It works exactly like Puma with a single thread setting Puma config process and threadLet s say you use the Puma server to run the Rails application The Puma is configured to run process worker and it has only thread The puma process can open up to connections to the database because the pool option is defined as in config database yml Typically there are fewer connections than that because when you run process and only thread only connection to the Postgres database will be needed to make a database query Sometimes the database connection might be dead In such a case ActiveRecord can open a new connection and then you may end up with active connections In the worst case scenario when connections would be dead then Rails can open connections max Puma config process and threadsIf you use threads in a single Puma process worker then it means those threads can use the same pool of DB connections within the Puma process It means that DB connections will be open out of possible If any connection is dead then more connections can be opened until the connection pool limit is reached Puma config processes and threads per processIf you run Puma processes workers and each process has threads then it means that each single process will open DB connections because you have threads per process You have processes so it means at the start of your application there might be DB connections open Each process has its pool so you have pools Each pool can open up to DB connections It means that in the worst case scenario there can be even connections created to the database Assuming you use threads per Puma process it s good to have the pool option set to some spare connections It allows ActiveRecord to open a new connection if one of the DB connections is dead Puma config processes and threads and web dynos on HerokuIf you use Heroku to host your application it allows scaling your web application horizontally by adding more servers dynos Assume you run your application on servers Heroku dynos each dyno is running Puma processes and each process has threads It means at the start your application may open connections to the database Here is why dynos X Puma processes X Puma threads DB connections dynos X Puma process X Pool size Total pool size It means that in the worst case your application may open DB connections Autoscaling web applicationIf you autoscale your web servers by adding more servers during the peak web traffic you need to be careful Ensure your application stays within the Postgres max connections limit The above example shows you how to calculate expected opened DB connections and the worst case scenario Please adjust your pool size to ensure that you will be below the max connections limit for your database engine in the worst case scenario What else can open DB connections We just talked about a webserver like Puma that can open connections and consume your max DB connections limit But other non web processes can do it as well You run Rails console on production in a Heroku dyno heroku run bin rails console app my app name It runs an instance of your Rails app and DB connection will be open In the worst case scenario the number of connections defined in the pool can be opened But it s unlikely that your DB connections would go dead So the whole pool limit shouldn t be used You run scheduled rake tasks via Heroku Scheduler cron like tool If the rake tasks are performed periodically they need to open a connection to the DB so that at least DB connection is used from the pool per rake task Imagine you have rake tasks that are started every hour It means you need available DB connections every hour It can be easy to miss this if you base your estimation on just the web connections You use background workers like Sidekiq to perform async jobs Your jobs may open DB connections We will talk about it later Background worker Sidekiq and ActiveRecord poolSidekiq process will use the pool defined in config database yml similarly as Puma All Sidekiq threads in a Sidekiq process can use a common pool of connections If you run multiple servers Heroku dynos then it works similarly to the Puma example servers dynos X Sidekiq process X Sidekiq threads DB connections will be open You need to have a pool size of at least in config database yml because Sidekiq by default uses threads If you use a pool size lower than then Sidekiq threads will be fighting for access to limited connections in the pool It could be fine for some time but you should be aware that this can increase your job s processing time because not all Sidekiq threads will use DB connections in parallel It can also lead to a problem described here Sidekiq and Redis database connectionsSidekiq uses the Redis database to store async jobs It would be best if you calculate DB connections to Redis as well as Postgres connections A Sidekiq server process requires at least concurrency connections The concurrency option is the number of Sidekiq threads per Sidekiq process Using the previous example servers dynos X Sidekiq process X Sidekiq threads servers dynos X Sidekiq process X Redis connections required More in Sidekiq docs Redis database connectionsIf you use Redis for processing background jobs then it s not just the Sidekiq process that is using Redis connections Your Puma process and threads can use Redis to add new jobs to the Sidekiq queue as well Typically you will have Redis connection per Puma thread If you explicitly open a new Redis connection with Redis new this can create a new connection per the Puma thread as well SummaryWe covered a few examples of Postgres and Redis on calculating DB connections needed by your Rails application I hope this will give you a better understanding of how to estimate how many DB connections you need on your database level to serve your application s demands properly If you are looking to improve your Rails application workflow please consider checking how to run automated tests in parallel on your CI server with Knapsack Pro	2021-05-11 14:04:15
海外TECH	DEV Community	How we choose programming languages at Typeable	https://dev.to/typeable/how-we-choose-programming-languages-at-typeable-3mnc	How we choose programming languages at TypeableAuthor Denis RedozubovI was asked several times why I prefer using such programming languages as Haskell and Rust since they are not the most widely used and popular tools I ve written this post to demystify what is going on in my head when I think about the technology selection Developing software that must meet the requirements for long term operation and defined reliability level is in a sense similar to a chess play In both cases it s rather difficult for the human brain to comprehend scenarios Experience is of great importance and every move choice can be critical Further resemblance implies that just like in chess development is very much positional i e a whole set of moves can be focused on preparation for a maneuver which results in winning a single pawn It might appear that it s merely one pawn but in a serious game it may become a considerable advantage Similarly to a positional game over the chess board the development and evolution of large scale projects involve constant decision making focused on solving major tasks or implementing the project requirements The effect of all even minor solutions tends to accumulate by the endgame or by the moment the software product is in operation However the difference complicating the situation is that unlike chess software development is not solved using a computer You can t find the best moves just by running a computer engine That is why it is necessary to make many decisions incrementally leading us to this goal and all means of improving our position are worth using In the nutshell solutions can be divided into several categories architectural procedural and instrumental Architectural solutions show the way we structure the project Procedures define how we organize the work process and assure the implementation quality and correctness Instruments in their turn determine what the development team should use to achieve the goal Today the end to end software development is carried out using a large number of tools you need to formalize the requirements and the development process write the software code and test it assemble the release etc Despite this flow of tasks selection of programming language can be of the greatest importance because this choice determines the following set of parameters Performance baseline Peculiarities of the software distribution and operation for example the interpreter s requirement or the static linking ability Ecosystem of reusable libraries and components I d like to note that it is not only the number of libraries that matters but also the quality of those relevant for you Possibilities of parallel concurrent asynchronous operation of the programs which may be important for many systems The difficulty people face when learning the technology which influences significantly both the language community and the developer retraining Language expressiveness which is somewhat subjective but still being felt by developers Additionally the selection of programming language can have a strong influence on the structure of development For instance the language ecosystem tools may determine the way unit tests are written and the tests scope A good infrastructure for property tests can give a boost to move in this direction while the lack of good infrastructure for unit tests can make their development and support more challenging The tools also influence architecture related issues reuse of the system modules is linked to how easy it is from the conceptual viewpoint to divide the units and structure the code For instance explicit work with the effect systems enables better code generalization and allows making sure that the software code unit doesn t perform any input output operations such as network and disk operations This allows talking about the safety and architecture Considering this you should be aware that the correct selection of programming language for your project and team may have far reaching implications Keeping in mind the chess analogy we remember that every minor advantage contributes a point in favor of the language and can play a significant role in a large scale development It should also be noted that I m talking about selecting the development tools in situations which set no strict constraints on technology selection relating for instance to a large ecosystems already written in a certain language At Typeable we are guided by the following reasons for general purpose languages The programming language should support static typing This allows the developer to reduce the duration of each iteration of the code modification and validation This also allows reducing the number of bugs significantly both in terms of functional requirements and software safety Algebraic data types it s difficult to overestimate the influence of this feature as soon as you start using it This is a simple feature absolutely necessary for invariant modeling Sum types are also so indispensable that selecting a language where you need to simulate them using other constructs means creating obstacles at the first step Flexibility of support and execution of multithreaded programs Languages with GIL Global Interpreter Lock fail to meet this requirement from the very beginning It s desirable to be able to maximize the hardware utilization and work with sufficiently high level abstractions A sufficient ecosystem of libraries We also subjectively assess their quality We don t think it necessary to connect everything in the form of libraries but such basic things as bindings to popular databases should be available Clear minds in the community of developers who work with this language A developer we would like to see in our team should be interested in CS and development This is opposed by “easy to learn technologies tempting people to join IT for the sake of easy money which greatly dilutes the workforce We should have programming languages in our toolbox that allow creating the software meeting strict time and memory requirements Considering all of the above our toolbox should allow us to hold a steady position in any project going our way Going back to the chess analogy these are our principles that let us play a highly positional game Positional game is a game aimed at creating a long term position that opens up possibilities for the player and minimizes the weaknesses It is opposed to an attack oriented game i e “sharp game associated with higher risks The attacking player strives to end the game before the opponent is able to take up a strong defense Sharp development includes programming contests MVP for marketing experiments many data science tasks and in many cases software development for Computer Science publications They are similar in that they usually don t require any long term support as they just have to work for a definite period of time On the other hand positional game means a long term play where maintainability and updateability are the key characteristics This is exactly what we do and we need a solid foundation to be sure that the software we write and update can operate for a long time Though such projects can also start as MVP they are based on quite different assumptions So why do we select the technology based on exactly these considerations Multiple reasons can be given First of all it s a good idea to exclude the issues of technology fashion and trendiness to improve predictability over a large timespan Even though a time proven compiler with an active community is a conservative option this choice is reliable in contrast to new flashing options popping up every year Surely some of them will move from the last category to the first one but we will know this only later probably in a number of years Instead of the fashion trends we strive to use the fundamental Computer Science and the great number of research works devoted to this topic which have been applied in the programming languages we use For example the type theory is a discipline close to both mathematics and CS dealing with the fundamental issues of requirements formalization This is exactly what we need to write software Besides this is the combined experience of other people engaged in exact sciences and I believe it s absurd to ignore this experience It makes more sense to take such discipline as a basis rather than use nothing or use a subjective opinion based on the personal experience of a particular individual Secondly we are looking for the programming languages and compilers embracing the largest possible number of our principles This is why in addition to our favorite Haskell we ve put Rust in our toolbox For real time requirements and strict constraints on memory utilization we need something rather low level The typing strictness in C is still far from perfect so if we can use Rust for such tasks we d prefer doing this The third reason is that we create software primarily for our clients and we d like to protect them from our biases That s why we can t exceed a certain risk level agreed with the client when we select a tool But even under these conditions we ve got rather marginal technologies such as GHCJS because the complex analysis of pros and cons still produced an attractive picture for us and our clients We wrote already about how we arrived at this decision  Elm vs Reflex All means and theoretical justifications are worth using when you work with large code bases and complex software as you have to keep this complexity in check somehow Our idea of a correct approach is to protect every pawn improve our position gradually and carefully so that the project could exist in a good and stable state until the moment it ll play pivotal role for our clients businesses	2021-05-11 14:03:40
海外TECH	DEV Community	MovingPoint-Lightweight-Java-2D-Game-Engine	https://dev.to/marcosteinke/movingpoint-lightweight-java-2d-game-engine-2m7l	MovingPoint Lightweight Java D Game EngineFind repo here Beginner Friendly EducationalI love programming and I also love teaching it to other persons so the main goal of MovingPoint is to bring new motivated talents into programming A lot of people dream of creating their own games MovingPoint gives them a first impression of Game Design Even childs with basic Java skills could use this to create simple games like TicTacToe or Snake Operating System Independencesince MovingPoint is written in pure Java you can run it on any Operating System Hardware IndependenceMovingPoint is lightweight you do not need the latest hardware to build your games You also do not need to import all modules only use the code which you need to build your project Use all Java libraries Yes it is true You can run any libraries and connect them to MovingPoint You are able to create Browsergames by running a Java Webapplication and importing MovingPoint Also usable to create Android Apps by using Android Studio Open sourceSince I am coding for around years and I tried out many different things this is my first try on writing a Game Engine so I want everybody to help me with the development You are able to use the Engine as you want to Modify it give me tips and together we can create a new experience of Game Design	2021-05-11 14:02:39
海外TECH	DEV Community	POINTERS IN C-LANGUAGE	https://dev.to/jahnavi1351/pointers-in-c-language-4oie	POINTERS IN C LANGUAGE POINTERS IN C•Every variable is a memory location and every memory location has its address defined which can be accessed using ampersand amp operator which denotes an address in memory •A pointer is a variable whose value is the address of another variable i e direct address of the memory location Like any variable or constant you must declare a pointer before using it to store any variable address •The general form of a pointer variable declaration is type var name Here type is the pointer s base type it must be a valid C datatype var name is the name of the pointer variable used to declare a pointer •Some of the valid pointer declarations are as follows int ip pointer to an integer double dp pointer to a double float fp pointer to a float char ch pointer to a character •The actual data type of the value of all pointers whether integer float character or otherwise is the same a long hexadecimal number that represents a memory address The only difference between pointers of different data types is the data type of the variable or constant that the pointer points to USAGE OF POINTERS a We define a pointer variable b Assign the address of a variable to a pointer c Finally access the value at the address available in the pointer variable •This is done by using unary operator that returns the value of the variable located at the address specified by its operand •Example include int main int var actual variable declaration int ip pointer variable declaration ip amp var store address of var in pointer variable printf Address of var variable x n amp var address stored in pointer variable printf Address stored in ip variable x n ip access the value using the pointer printf Value of ip variable d n ip return •When the above code is compiled and executed it produces the following result Address of var variable bffdbc Address stored in ip variable bffdbc Value of ip variable NULL POINTERS•It is always a good practice to assign a NULL value to a pointer variable in case you do not have an exact address to be assigned This is done at the time of variable declaration A pointer that is assigned NULL is called a null pointer •The NULL pointer is a constant with a value of zero defined in several standard libraries Consider the following program •EXAMPLE include int main int ptr NULL printf The value of ptr is x n ptr return •When the above code is compiled and executed it produces the following result The value of ptr is In most of the operating systems programs are not permitted to access memory at address because that memory is reserved by the operating system However the memory address has special significance it signals that the pointer is not intended to point to an accessible memory location But by convention if a pointer contains the null zero value it is assumed to point to nothing To check for a null pointer you can use an if statement as follows if ptr succeeds if p is not null if ptr succeeds if p is null	2021-05-11 14:02:29
海外TECH	DEV Community	📷 survAPI Surveillance Camera Analysis	https://dev.to/marcosteinke/survapi-surveillance-camera-analysis-3ago	survAPI Surveillance Camera AnalysisNeed surveillance but low on server capacity Train the camera to know when to record find my Repository here Introduction This implementation demonstrates a Security Camera Software which was written in javascript and uses cocossd offered by ml to detect objects The application is secured using express session and bcrypt This way only authenticated users can access your surveillance and you are able to allow registrations and create new roles to control this system Problem A business needs a security camera but is low on server capacity Thatswhy the business can not store videos Solution Using Machine Learning we can tell the camera when it has objects in view and use a lightweight backend to store the timestamps and also the type of objects which where detected Classification After detection the software later classifies them as certain targets PersistenceIf the classified object is one of the targets it will be persisted in the database by giving information on its type and also adding a timestamp and date Now we know when to start recording and stop after a predefined amount of time passed Improvements over conventional Security Cameras installation is very easy and very customizable due to Open Source Technologya clean webinterface makes your cameras accessible and configurabledetection of persons is a standard problem of Machine Learning and already has a very high precisiondestroy video material in which nothing happens you will only store critical important momentsadvance your security by getting additional information from your camera super simple setup modern dashboard and webpages to access the cameras combine any hardware with this software SurvAPI The included surveillance API also offers all of the analysis tool to be called from other frameworks lightweight and fast optimized amount of video data Machine Learning used to detect certain targets predefine intervals to control data produced by the camera very simple database structurehigh security level by using bcrypt️Architecture The project will be separated into the subsystems Camera Surveillance Database Webviews where each subsystem exactly solves one of the given business problems To guarantee clean code this project will profit from Domain Driven Design and from Self Contained System s Camera The subsystem will fulfill the HARDWARE part in this project All types of cameras which you find right below under Compatibility will be connected via this subsystem It defines a domain model which projects the real world properties of cameras into code and offers its configured cameras to all of the other subsystems All of the input will run through this subsystem Surveillance The surveillance will process video material received from any video source configured in the Camera subsystem It makes use of ML and analyses the material based on the admins preferences The analysis results will be persisted in the Database subsystem It usually is not a separate subsystem but for this project it will do best if the database can completely be substituted behind an interface which connects the Webviews and the Surveillance to it Database Use any type of database you want and store all of the analysis results You can access the persisted data by using the Webviews or build your own UI to access it Webviews Basically a frontend which can be accessed from any webbrowser You can configure the cameras inspect detections in a nice way and get watch live material from your surveillance cameras	2021-05-11 14:01:29
海外TECH	DEV Community	How To Create A Simple Alert For An onbeforeunload Event (Closing Browser or Navigating Away From Page)	https://dev.to/tiaeastwood/how-to-create-a-simple-alert-for-an-onbeforeunload-event-closing-browser-or-navigating-away-from-page-6ph	How To Create A Simple Alert For An onbeforeunload Event Closing Browser or Navigating Away From Page Sorry I couldn t think of a shorter title Here is a useful little snippet for if you have a page like a checkout or a survey and you want to warn people about leaving the page before they ve completed it window onbeforeunload event gt if whatever your condition is here return true The alert gives the user the option to confirm or cancel their navigation Alerts should never stop someone from leaving a page or closing their browser though that s a big no no An onbeforeunload event occurs when the document the current page of your site application is about to be unloaded closed exited A example of this would be someone closing the browser window or clicking a link to a different page Most browsers will show a default message like changes you ve made will not be saved You can t edit this message but it does the job as a warning Due to this you don t need to return any specific content or message in the function just return true in order for it to work This function will be called when an onbeforeunload event occurs If the condition inside is met then the function will return true and the alert will be shown So all you need to do is apply a condition to decide when the alert will be shown For example if using this in a React application then the condition could be based on a certain state For example const isSurveyCompleted setIsSurveyCompleted useState false window onbeforeunload event gt if isSurveyCompleted return true the alert will appear if the user tries to close the browser window because they haven t completed the survey There are other ways of achieving this sort of behaviour such as using Prompt in react router but if you re just looking for a simple solution then I hope this helps If you have anything to add please leave a comment	2021-05-11 14:01:23
Apple	AppleInsider - Frontpage News	Amazon's Wondery joins Apple Podcast Subscriptions	https://appleinsider.com/articles/21/05/11/amazons-wondery-joins-apple-podcast-subscriptions?utm_medium=rss	Amazon x s Wondery joins Apple Podcast SubscriptionsApple has secured content for Apple Podcast Subscriptions from Wondery in a deal with the Amazon owned podcast studio that will have some of its Wondery subscription content available through Apple s platform Launched at its Spring Loaded event Apple Subscription Podcasts allows podcast creators to set up monthly and annual subscriptions for shows Following the launch Apple has now managed to gain a number of high profile shows that will be available via the subscription option In the deal with Wondery podcasts offered in the Wondery subscription service will be available through Apple Podcast Subscriptions reports The Hollywood Reporter The podcasts will be offered ad free just as under Wondery though ad supported free versions will also be available for listening Read more	2021-05-11 14:26:53
Apple	AppleInsider - Frontpage News	How to select Apple TV screensavers and find out where they were filmed	https://appleinsider.com/articles/21/05/11/how-to-select-apple-tv-screensavers-and-find-out-where-they-were-filmed?utm_medium=rss	How to select Apple TV screensavers and find out where they were filmedThey are the unexpected extra appeal of an Apple TV K but those beautiful screensavers do make you want to pick your favorite and find out where they were filmed Here s how to do both We re not saying that the screensavers are better than some of the shows you can watch on Apple TV It sounds like the most trivial part of Apple TV K until you ve seen it If you ve ever had any Apple TV then you will have seen the screensavers and they are nothing short of beautiful Read more	2021-05-11 14:21:45
Apple	AppleInsider - Frontpage News	UK class action over App Store commission could cost Apple $2B	https://appleinsider.com/articles/21/05/11/uk-class-action-over-app-store-commission-could-cost-apple-2b?utm_medium=rss	UK class action over App Store commission could cost Apple BA class action lawsuit filed with London s Competition Appeal Tribunal takes issue with Apple s customary App Store commission rates arguing the developer fee is passed on to consumers In a press release Tuesday claimants in the case argue Apple has overcharged nearly million UK App Store customers for years by imposing an excessive and unlawful cut of in app purchases on developers The group is seeking damages of up to billion pounds reports the BBC Read more	2021-05-11 14:25:37
海外TECH	Engadget	Facebook ordered to stop collecting data on German WhatsApp users	https://www.engadget.com/facebook-whatsapp-privacy-policy-germany-data-collection-ban-143607696.html	emergency	2021-05-11 14:36:07
海外TECH	Engadget	Akai brings classic MPC looks to its One groovebox	https://www.engadget.com/akai-mpc-one-retro-music-production-machine-142916111.html	music	2021-05-11 14:29:16
Cisco	Cisco Blog	Celebrating MinuteClinic as it Transforms the Health of People and Communities	https://blogs.cisco.com/healthcare/celebrating-minuteclinic-as-it-transforms-the-health-of-people-and-communities	Celebrating MinuteClinic as it Transforms the Health of People and CommunitiesCisco customer CVS MinuteClinic wins the ANCC Pathway Awardーand more importantly makes a difference in the communities they serve	2021-05-11 14:19:14
Cisco	Cisco Blog	Cisco Welcomes Waldo McMillian as Head of the Washington, DC Office	https://blogs.cisco.com/gov/cisco-welcomes-waldo-mcmillian-as-head-of-the-washington-dc-office	Cisco Welcomes Waldo McMillian as Head of the Washington DC OfficeThis is a very exciting moment in Washington The Biden Administration and a new Congress are working to accelerate a recovery that is swift and effective Federal agencies are harnessing the potential of technology to evolve the way we work learn receive healthcare and even govern The opportunity for Cisco to share our technology expertise	2021-05-11 14:17:02
金融	RSS FILE - 日本証券業協会	株券等貸借取引状況（週間）	https://www.jsda.or.jp/shiryoshitsu/toukei/kabu-taiw/index.html	貸借	2021-05-11 15:30:00
金融	RSS FILE - 日本証券業協会	インターネット取引に係るシステム障害件数	https://www.jsda.or.jp/shiryoshitsu/toukei/inter/index.html	取引	2021-05-11 15:20:00
金融	金融庁ホームページ	審判期日の予定を更新しました。	https://www.fsa.go.jp/policy/kachoukin/06.html	期日	2021-05-11 16:00:00
金融	金融庁ホームページ	金融庁職員の新型コロナウイルス感染について公表しました。	https://www.fsa.go.jp/news/r2/sonota/20210511.html	新型コロナウイルス	2021-05-11 15:00:00
海外ニュース	Japan Times latest articles	China makes us rethink capitalism	https://www.japantimes.co.jp/opinion/2021/05/11/commentary/world-commentary/china-and-capitalism/	animal	2021-05-12 00:45:25
海外ニュース	Japan Times latest articles	Five things moms gained during COVID-19 — and should refuse to give up	https://www.japantimes.co.jp/opinion/2021/05/11/commentary/world-commentary/womens-issues-five-things-moms-gained-during-covid-19/	Five things moms gained during COVID ー and should refuse to give upWhile the pandemic has brought many of us to the brink of our sanity it has also forced many organizations to give moms long overdue concessions	2021-05-12 00:33:47
ニュース	BBC News - Home	Ballymurphy Inquest: Coroner finds 10 victims were innocent	https://www.bbc.co.uk/news/uk-northern-ireland-56986784	operation	2021-05-11 14:34:35
ニュース	BBC News - Home	Covid in Scotland: Hugging and indoor visits to resume from Monday	https://www.bbc.co.uk/news/uk-scotland-57070970	nicola	2021-05-11 14:06:06
ニュース	BBC News - Home	Fred West police search Gloucester cafe for Mary Bastholm	https://www.bbc.co.uk/news/uk-england-gloucestershire-57070279	bastholm	2021-05-11 14:12:21
ニュース	BBC News - Home	Death toll mounts as Israel-Gaza violence escalates	https://www.bbc.co.uk/news/world-middle-east-57066275	jerusalem	2021-05-11 14:06:39
北海道	北海道新聞	ＮＹ株、一時３００ドル超安　高値警戒感、ＩＴ下落	https://www.hokkaido-np.co.jp/article/542761/	高値	2021-05-11 23:07:00
仮想通貨	BITPRESS（ビットプレス）	ビットポイントジャパン、5/10付で第一種金融商品取引業登録に関するお知らせ	https://bitpress.jp/count2/3_11_12483	金融商品取引業	2021-05-11 23:10:05
仮想通貨	BITPRESS（ビットプレス）	[Fintech Journal] bitFlyerやLayerX、JDDが語るブロックチェーン、なぜ「20年前のECと同じ」なのか	https://bitpress.jp/count2/3_9_12482	fintechjournalbitflyer	2021-05-11 23:06:37