Tutorial by Examples: r

Vim supports the use of regular expressions when searching through a file. The character to indicate that you wish to perform a search is /. The simplest search you can perform is the following /if This will search the entire file for all instances of if. However, our search if is actually a r...

// You need a writable database to update a row final SQLiteDatabase database = openHelper.getWritableDatabase(); // Create a ContentValues instance which contains the up to date data for each column // Unlike when inserting data you need to specify the value for the PRIMARY KEY column as well ...

Transactions can be used to make multiple changes to the database atomically. Any normal transaction follows this pattern: // You need a writable database to perform transactions final SQLiteDatabase database = openHelper.getWritableDatabase(); // This call starts a transaction database.beginT...

Orders Table CustomerIdProductIdQuantityPrice12510013220014150021450356700 To check for customers who have ordered both - ProductID 2 and 3, HAVING can be used select customerId from orders where productID in (2,3) group by customerId having count(distinct productID) = 2 Return value:...

Following statement matches all records having FName that starts with a letter from A to F from Employees Table. SELECT * FROM Employees WHERE FName LIKE '[A-F]%'

We can destructure lists of compound objects CL-USER> (loop for (a . b) in '((1 . 2) (3 . 4) (5 . 6)) collect a) (1 3 5) CL-USER> (loop for (a . b) in '((1 . 2) (3 . 4) (5 . 6)) collect b) (2 4 6) CL-USER> (loop for (a b c) in '((1 2 3) (4 5 6) (7 8 9) (10 11 12)) collect b) (2 5 8 11...

package main import ( "fmt" "io/ioutil" ) func main() { files, err := ioutil.ReadDir(".") if err != nil { panic(err) } fmt.Println("Folders in the current directory:") for _, fileInfo := range files { ...

You need to create a new local copy of the repository with the command git svn clone SVN_REPO_ROOT_URL [DEST_FOLDER_PATH] -T TRUNK_REPO_PATH -t TAGS_REPO_PATH -b BRANCHES_REPO_PATH If your SVN repository follows the standard layout (trunk, branches, tags folders) you can save some typing: git svn...

The equivalent to git pull is the command git svn rebase This retrieves all the changes from the SVN repository and applies them on top of your local commits in your current branch. You can also use the command git svn fetch to retrieve the changes from the SVN repository and bring them to ...

Just use your local git repository as a normal git repo, with the normal git commands: git add FILE and git checkout -- FILE To stage/unstage a file git commit To save your changes. Those commits will be local and will not be "pushed" to the SVN repo, just like in a normal git reposito...

git does not recognice the concept of folders, it just works with files and their filepaths. This means git does not track empty folders. SVN, however, does. Using git-svn means that, by default, any change you do involving empty folders with git will not be propagated to SVN. Using the --rmdir fl...

This simple CUDA program demonstrates how to write a function that will execute on the GPU (aka "device"). The CPU, or "host", creates CUDA threads by calling special functions called "kernels". CUDA programs are C++ programs with additional syntax. To see how it works...

Go to File -> Settings -> Editor -> Colors & Fonts -> Android Logcat Change the colors as you need: Choose the appropriate color:

Some basic types and classes in Java are fundamentally mutable. For example, all array types are mutable, and so are classes like java.util.Data. This can be awkward in situations where an immutable type is mandated. One way to deal with this is to create an immutable wrapper for the mutable type...

enable_shared_from_this enables you to get a valid shared_ptr instance to this. By deriving your class from the class template enable_shared_from_this, you inherit a method shared_from_this that returns a shared_ptr instance to this. Note that the object must be created as a shared_ptr in first pl...

This example shows how to create a delegate that encapsulates the method that returns the current time static DateTime UTCNow() { return DateTime.UtcNow; } static DateTime LocalNow() { return DateTime.Now; } static void Main(string[] args) { Func<DateTime> method = U...

static int Sum(int a, int b) { return a + b; } static int Multiplication(int a, int b) { return a * b; } static void Main(string[] args) { Func<int, int, int> method = Sum; // method points to the Sum method // that retuns 1 int variable and takes 2 int vari...

Func also supports Covariant & Contravariant // Simple hierarchy of classes. public class Person { } public class Employee : Person { } class Program { static Employee FindByTitle(String title) { // This is a stub for a method that returns // an employee that h...

This example demonstrates how to fetch the URI's of system ringtones (RingtoneManager.TYPE_RINGTONE): private List<Uri> loadLocalRingtonesUris() { List<Uri> alarms = new ArrayList<>(); try { RingtoneManager ringtoneMgr = new RingtoneManager(getActivi...

This example shows how to use a request interceptor with OkHttp. This has numerous use cases such as: Adding universal header to the request. E.g. authenticating a request Debugging networked applications Retrieving raw response Logging network transaction etc. Set custom user agent Retrof...