Tutorial by Examples: u

If a target matches multiple pattern rules, make will use the one whose prerequisites exist or can be built. For example: %.o: %.c $(CC) $(CFLAGS) -c $< -o $@ %.o: %.s $(AS) $(ASFLAGS) $< -o $@ Will compile foo.c to foo.o or assemble foo.s to foo.o, depending on which one of foo...

If the target pattern doesn't contain slashes, make will remove the directory part from the target it's trying to build before matching. The directory will then be put in front of the stem. When the stem is used to build the target name and prerequisites, the directory part is stripped from it, the ...

Pattern rules can have multiple targets but, unlike normal rules, the recipe is responsible for making all the targets. For example: debug/%.o release/%.o: %.c $(CC) $(CFLAGS_DEBUG) -c $< -o debug/$*.o $(CC) $(CFLAGS_RELEASE) -c $< -o release/$*.o Is a valid rule, which will buil...

Introduced in iOS 9, all endpoints must adhere to the HTTPS specification. Any endpoints not using SSL will fail with a warning in the console log. To your application it will appear that the internet connection failed. To configure exceptions: Place the following in your Info.plist file: Allow...

Passing a 2d array to a functions seems simple and obvious and we happily write: #include <stdio.h> #include <stdlib.h> #define ROWS 3 #define COLS 2 void fun1(int **, int, int); int main() { int array_2D[ROWS][COLS] = { {1, 2}, {3, 4}, {5, 6} }; int n = ROWS; int m...

If you want to add a UIImageView to the center of the screen with width and height of 100 pixel, you need to set center x constraint and center y constraint to the superview from the UIImageView and width, height constraint to the UIIMageView. Here is the code. There is way to do this in storyboard ...

Detailed instructions on getting google-cloud-platform set up or installed.

A NullReferenceException is thrown when you try to access a non-static member (property, method, field or event) of a reference object but it is null. Car myFirstCar = new Car(); Car mySecondCar = null; Color myFirstColor = myFirstCar.Color; // No problem as myFirstCar exists / is not null Color...

If you need to listen for changes to the page selected you can implement the ViewPager.OnPageChangeListener listener on the ViewPager: viewPager.addOnPageChangeListener(new OnPageChangeListener() { // This method will be invoked when a new page becomes selected. Animation is not necessar...

public class CreateArrayWithValues { public static void main(String[] args){ // Initializes an array of Strings with values String[] myArray = {"this", "array", "has", "six", "initial", "values"}; System.out....

Xamarin is becoming more and more popular - it is hard to decide when to use Xamarin.Forms and when Xamarin.Platform (so Xamarin.iOS and Xamarin.Android). First of all you should know for what kind of applications you can use Xamarin.Forms: Prototypes - to visualize how your application will l...

Detailed instructions on getting scenekit set up or installed.

Every time jQuery is called, by using $() or jQuery(), internally it is creating a new instance of jQuery. This is the source code which shows the new instance: // Define a local copy of jQuery jQuery = function( selector, context ) { // The jQuery object is actually just the init construct...

In some cases, you would need to execute SQL query placed in string. EXEC, EXECUTE, or system procedure sp_executesql can execute any SQL query provided as string: sp_executesql N'SELECT * FROM sys.objects' -- or sp_executesql @stmt = N'SELECT * FROM sys.objects' -- or EXEC sp_executesql N'SEL...

You can execute SQL query as different user using AS USER = 'name of database user' EXEC(N'SELECT * FROM product') AS USER = 'dbo' SQL query will be executed under dbo database user. All permission checks applicable to dbo user will be checked on SQL query.

Django's built-in User model is not always appropiate for some kinds of projects. On some sites it might make more sense to use an email address instead of a username for instance. You can override the default User model adding your customized User model to the AUTH_USER_MODEL setting, in your proj...

Your code will not work in projects where you reference the User model (and where the AUTH_USER_MODEL setting has been changed) directly. For example: if you want to create Post model for a blog with a customized User model, you should specify the custom User model like this: from django.conf impo...

There are many reasons a write operation may fail. A frequent one is because your security rules reject the operation, for example because you're not authenticated (by default a database can only be accessed by an authenticated user). You can see these security rule violations in the output of your...

SQL Server 2008 The ROW_NUMBER function can assign an incrementing number to each row in a result set. Combined with a Common Table Expression that uses a BETWEEN operator, it is possible to create 'pages' of result sets. For example: page one containing results 1-10, page two containing results 11...

In earlier versions of SQL Server, developers had to use double sorting combined with the TOP keyword to return rows in a page: SELECT TOP 10 * FROM ( SELECT TOP 50 object_id, name, type, create_date FROM sys.objects ORDER BY name ASC ) AS data ...