Tutorial by Examples: f

In most object oriented languages, allocating memory for an object and initializing it is an atomic operation: // Both allocates memory and calls the constructor MyClass object = new MyClass(); In Objective-C, these are separate operations. The class methods alloc (and its historic sibling allo...

These components will have changing States. import React, { Component } from 'react' import { View, Text, AppRegistry } from 'react-native' class Example extends Component { constructor (props) { super(props) this.state = { name: "Sriraman" } } render ...

Consider the following example: public final class Person { private final String firstName; private final String lastName; public Person(String firstName, String lastName) { this.firstName = (firstName == null) ? "" : firstName; this.lastName = (lastN...

Use .PHONY to specify the targets that are not files, e.g., clean or mrproper. Good example .PHONY: clean clean: rm *.o temp Bad example clean: rm *.o temp In the good example make knows that clean is not a file, therefore it will not search if it is or not up to date and will ex...

Data frames are R's tabular data structure. They can be written to or read from in a variety of ways. This example illustrates a couple common situations. See the links at the end for other resources. Writing Before making the example data below, make sure you're in a folder you want to write to....

project('projectA') { task A(dependsOn: ':projectB:B') << { println 'Hello from A' } } project('projectB') { task B << { println 'Hello from B' } } To refer to a task in another project, you prefix the name of the task with the path of the pr...

Exporting using base R Data can be written to a CSV file using write.csv(): write.csv(mtcars, "mtcars.csv") Commonly-specified parameters include row.names = FALSE and na = "". Exporting using packages readr::write_csv is significantly faster than write.csv and does not ...

context.globalCompositeOperation = "source-over" "source-over" compositing [default], places all new drawings over any existing drawings. context.globalCompositeOperation='source-over'; // the default context.drawImage(background,0,0); context.drawImage(parachuter,0,0); ...

task A << { println 'Hello from A' } task B << { println 'Hello from B' } B.mustRunAfter A The B.mustRunAfter A line tells Gradle to run task after task specified as an argument. And the output is: > gradle -q B A Hello from A Hello from B The ordering rule d...

Custom sounds may be provided for notifications generated by your app. When the system displays an alert for a local notification or badges an app icon, it plays this sound (so long as the user has not disabled notification sounds). The default value is nil which means no sound is played for your n...

General Listening This example shows how to listen for a specific advertisement. BluetoothLEAdvertisementWatcher watcher = new BluetoothLEAdvertisementWatcher(); // Use active listening if you want to receive Scan Response packets as well // this will have a greater power cost. watcher.Scanni...

Considering that most debuggers are not aware of #define macros, but can check enum constants, it may be desirable to do something like this: #if __STDC_VERSION__ < 199900L typedef enum { false, true } bool; /* Modern C code might expect these to be macros. */ # ifndef bool # define bool bo...

class Category(models.Model): name = models.CharField(max_length=20) class Product(models.Model): name = models.CharField(max_length=64) category = models.ForeignKey(Category, on_delete=models.PROTECT) To get the number products for each category: >>> categories = Ca...

Julia code can create, manipulate, and execute command literals, which execute in the OS's system environment. This is powerful but often makes programs less portable. A command literal can be created using the `` literal. Information can be interpolated using the $ interpolation syntax, as with st...

Sometimes you might have branches lying around that have already had their changes merged into master. This finds all branches that are not master that have no unique commits as compared to master. This is very useful for finding branches that were not deleted after the PR was merged into master. ...

It's important to handle exceptions in your service. When developing the service, you can set the WCF to provide more detailed information, adding this tag to configuration file, usually Web.config: <serviceDebug includeExceptionDetailInFaults="true"/> This tag must be placed w...

You can handle exceptions and throw a most friendly message like 'Unavailable service' throwing a FaultException: try { // your service logic here } catch (Exception ex) { // You can do something here, like log the original exception throw new FaultException("There was a pro...

The FaultException can also includes a FaultCode, that is a string data you can use to pass additional information, so the client can be able to distinguish different exceptions: try { // your service logic here } catch (Exception ex) { throw new FaultException("There was a proble...

Example implementation of a prime factorization algorithm. A prime factorization algorithm will find for a given number n a list of primes, such that if you multiply those primes you get n. The below implementation will add -1 to the list of prime factors in case n < 0. Note that there exists no ...

It took me a while to get this right, so I decided to share a solution because it might save someone else several days of trial and error. The problem: I want to be able to enable/disable WCF tracing in my C# .NET application and choose the trace output filename. I don't want users editing the .con...