Tutorial by Examples: ed

To take a photo, first we need to declare required permissions in AndroidManifest.xml. We need two permissions: Camera - to open camera app. If attribute required is set to true you will not be able to install this app if you don't have hardware camera. WRITE_EXTERNAL_STORAGE - This permission i...

def foo(li=[]): li.append(1) print(li) foo([2]) # Out: [2, 1] foo([3]) # Out: [3, 1] This code behaves as expected, but what if we don't pass an argument? foo() # Out: [1] As expected... foo() # Out: [1, 1] Not as expected... This is because default arguments of function...

In order to ssh into a server your identity's public key has to be added to the list of trusted keys. Most commonly this is done per-user: ssh-copy-id -i ~/.ssh/<identity>.pub <user>@<hostname> Which can be also done manually: cat ~/.ssh/<identity>.pub | ssh <user>...

This example shows how PLINQ can be used to calculate the even numbers between 1 and 10,000 using multiple threads. Order will be maintained in the resulting list, however keep in mind that AsOrdered may hurt performance for a large numbers of elements, so un-ordered processing is preferred when pos...

Ordered sequences may hurt performance when dealing with a large number of elements. To mitigate this, it's possible to call AsUnordered when the sequence order is no longer necessary. var sequence = Enumerable.Range(1, 10000).Select(x => -1 * x); // -1, -2, ... var evenNumbers = sequence.AsPar...

One of the most common errors in compilation happens during the linking stage. The error looks similar to this: $ gcc undefined_reference.c /tmp/ccoXhwF0.o: In function `main': undefined_reference.c:(.text+0x15): undefined reference to `foo' collect2: error: ld returned 1 exit status $ So l...

Any time SQL executed through an ADO connection needs to contain user input, it is considered best practice to parameterize it in order to minimize the chance of SQL injection. This method is also more readable than long concatenations and facilitates more robust and maintainable code (i.e. by using...

Dim lineOfHyphens As String 'Assign a string with 80 repeated hyphens lineOfHyphens = String$(80, "-")

Some properties are not automatically inherited from an element down to its' children. This is because those properties are typically desired to be unique to the element (or selection of elements) to which the property is applied to. Common such properties are margin, padding, background, display, e...

The default gnuplot command plot (also only p) plot dataset with columns, of the form of the data_set.dat file below. # Prototype of a gnuplot data set # data_set.dat # X - X^2 - 2*X - Random 0 0 0 5 1 1 2 15 1.4142 2 2.8284 1 2 ...

To initialize react-native init MyAwesomeProject To initialize with a specific version of React Native react-native init --version="0.36.0" MyAwesomeProject To Run for Android cd MyAwesomeProject react-native run-android To Run for iOS cd MyAwesomeProject react-native run-io...

Defines a new type based on an existing type. Its syntax mirrors that of a variable declaration. /* Byte can be used wherever `unsigned char` is needed */ typedef unsigned char Byte; /* Integer is the type used to declare an array consisting of a single int */ typedef int Integer[1]; /* Nod...

The reduce method reduces the collection to a single value, passing the result of each iteration into the subsequent iteration. Please see reduce method. The reduce method loops through each item with a collection and produces new result to the next iteration. Each result from the last iteration ...

Sometimes we need preserve whole model and transfer it across actions or even controllers. Storing model at session good solution for this type of requirements. If we combine this with powerful model binding features of MVC we get elegant way of doing so. We can create generic session based model bi...

Given a String containing the name of a class, it's Class object can be accessed using Class.forName: Class clazz = null; try { clazz = Class.forName("java.lang.Integer"); } catch (ClassNotFoundException ex) { throw new IllegalStateException(ex); } Java SE 1.2 It can be s...

// Print the multiplication table up to 5s for (int i = 1; i <= 5; i++) { for (int j = 1; j <= 5; j++) { int product = i * j; Console.WriteLine("{0} times {1} is {2}", i, j, product); } }

Constants in Go may be typed or untyped. For instance, given the following string literal: "bar" one might say that the type of the literal is string, however, this is not semantically correct. Instead, literals are Untyped string constants. It is a string (more correctly, its default ...

If you have only just popped it and the terminal is still open, you will still have the hash value printed by git stash pop on screen: $ git stash pop [...] Dropped refs/stash@{0} (2ca03e22256be97f9e40f08e6d6773c7d41dbfd1) (Note that git stash drop also produces the same line.) Otherwise, you...

[ alias ] ignored = ! git ls-files --others --ignored --exclude-standard --directory \ && git ls-files --others -i --exclude-standard Shows one line per file, so you can grep (only directories): $ git ignored | grep '/$' .yardoc/ doc/ Or count: ~$ git ignored | ...

Counting rows based on a specific column value: SELECT category, COUNT(*) AS item_count FROM item GROUP BY category; Getting average income by department: SELECT department, AVG(income) FROM employees GROUP BY department; The important thing is to select only columns specified in the GRO...