Tutorial by Examples: u

What we have is a list of credit cards and we'd like to calculate the premiums for all those cards that the credit card company has to pay out. The premiums themselves depend on the total number of credit cards, so that the company adjust them accordingly. We already have a function that calculate...

Sometimes auto may behave not quite as was expected by a programmer. It type deduces the expression, even when type deduction is not the right thing to do. As an example, when proxy objects are used in the code: std::vector<bool> flags{true, true, false}; auto flag = flags[0]; flags.push_...

While using decorator syntax (with the @) is convenient, it also a bit concealing. You can use properties directly, without decorators. The following Python 3.x example shows this: class A: p = 1234 def getX (self): return self._x def setX (self, value): self._x =...

Multi-Editing allows the user to edit text at several locations simultaneously. Multi-Editing is disabled by default: it can be enabled (resp. disabled) in Preferences > Editing by checking (resp. unchecking) the related checkbox. To use Multi-Editing, the user can Ctrl Click on the differe...

Column Editing enables the user to edit text on several lines as a vertical square zone. This feature is enabled by default. There are 3 ways to select a zone to edit: Maintain Alt+Shift and use Up/Down/Left/Right to select the zone to edit with direction keys Maintain Alt+Shift and click on t...

The fact that the garbage collection will clean up does not mean that you should wait for the garbage collection cycle to clean up. In particular you should not wait for garbage collection to close file handles, database connections and open network connections. for example: In the following code...

Any String can be evaluated at runtime. class Example def self.foo :foo end end eval "Example.foo" #=> :foo

Ruby keeps track of local variables and self variable via an object called binding. We can get binding of a scope with calling Kernel#binding and evaluate string inside a binding via Binding#eval. b = proc do local_variable = :local binding end.call b.eval "local_variable" #=&gt...

The instance_eval method is available on all objects. It evaluates code in the context of the receiver: object = Object.new object.instance_eval do @variable = :value end object.instance_variable_get :@variable # => :value instance_eval sets self to object for the duration of the co...

It is possible to compress an HTTP response message body more than once. The encoding names should then be separated by a comma in the order in which they were applied. For example, if a message has been compressed via deflate and then gzip, the header should look like: Content-Encoding: deflate, g...

R has a set of built in higher order functions: Map, Reduce, Filter, Find, Position, Negate. Map applies a given function to a list of values: words <- list("this", "is", "an", "example") Map(toupper, words) Reduce successively applies a binary functi...

If the file already exists, it will be overwritten! String fileName = "file.zip"; // name of the file String urlToGetFrom = "http://www.mywebsite.com/"; // URL to get it from String pathToSaveTo = "C:\\Users\\user\\"; // where to put it ...

There are a couple of builtin viewports, that each do different things. Here is a list of the names, and their descriptions: Viewport NameDescriptionStretchViewportWill stretch the screen. No black bars, but aspect ratio might be off.FitViewportWill maximize it's size based on the aspect ratio. Cou...

You can make your very own custom viewport. It may have black bars, and it may or may not keep it's aspect ratio, depending on how you program it. A custom viewport would look something like this: public class Tutorial extends Viewport. You would need to override update(width, height), but that's it...

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Using --where tag sqoop import \ --connect <rdbms-jdbc-url> \ --username <username> \ --password <password> \ --table <table-name> \ --where "<condition>" Example with Mysql: sqoop import \ --connect jdbc:mysql://mysql.example.com/testdb \ --userna...

In the light of the latest httpoxy vulnerabilities, there is another variable, that is widely misused. HTTP_X_FORWARDED_FOR is often used to detect the client IP address, but without any additional checks, this can lead to security issues, especially when this IP is later used for authentication or...

Suppose you want to prevent unauthorized users to access the page then you have to put barrier to them by authorizing access. We can do this by using spring-security which provides basic authentication by securing all HTTP end points. For that you need to add spring-security dependency to your proje...

As from version 5.4, PHP comes with built-in server. It can be used to run application without need to install other http server like nginx or apache. Built-in server is designed only in controller environment for development and testing purposes. It can be run with command php -S : To test it cr...

C99 Since C99, C has variable length arrays, VLA, that model arrays with bounds that are only known at initialization time. While you have to be careful not to allocate too large VLA (they might smash your stack), using pointers to VLA and using them in sizeof expressions is fine. double sumAll(si...