Tutorial by Examples: in

All published ISO standards are available for sale from the ISO store ( http://www.iso.org ). The working drafts of the C++ standards are publicly available for free though. The different versions of the standard: Upcoming (Sometimes referred as C++20 or C++2a): Current working draft (HTML-vers...

See this Q&A question if you don't know what race conditions are. The following code may be subject to race conditions : article = Article.objects.get(pk=69) article.views_count += 1 article.save() If views_count is equal to 1337, this will result in such query: UPDATE app_article SET vi...

Let's assume that we want to remove 2 upvotes from all the articles of the author with id 51. Doing this only with Python would execute N queries (N being the number of articles in the queryset): for article in Article.objects.filter(author_id=51): article.upvotes -= 2 article.save() ...

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:...

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 ...

The command git svn dcommit will create a SVN revision for each of your local git commits. As with SVN, your local git history must be in sync with the latest changes in the SVN repository, so if the command fails, try performing a git svn rebase first.

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...

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 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...

Please see here: Pointer Arithmetic