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require Exporter; This will ensure that the Exporter module is loaded at runtime if it hasn't already been imported. (See also: perldoc -f require.) N.B.: Most users should use modules rather than require them. Unlike use, require does not call the module's import method and is executed at runti...

use Cwd; This will import the Cwd module at compile time and import its default symbols, i.e. make some of the module's variables and functions available to the code using it. (See also: perldoc -f use.) Generally this is will do the right thing. Sometimes, however, you will want to control whic...

When multi-line (?m) modifier is turned off, ^ matches only the input string's beginning: For the regex ^He The following input strings match: Hedgehog\nFirst line\nLast line Help me, please He And the following input strings do not match: First line\nHedgehog\nLast line IHedgehog ...

If you need to use the ^ character in a character class (Character classes ), either put it somewhere other than the beginning of the class: [12^3] Or escape the ^ using a backslash \: [\^123] If you want to match the caret character itself outside a character class, you need to escape it: ...

Signal numbers can be synchronous (like SIGSEGV – segmentation fault) when they are triggered by a malfunctioning of the program itself or asynchronous (like SIGINT - interactive attention) when they are initiated from outside the program, e.g by a keypress as Cntrl-C. The signal() function is part...

To conditionally include a block of code, the preprocessor has several directives (e.g #if, #ifdef, #else, #endif, etc). /* Defines a conditional `printf` macro, which only prints if `DEBUG` * has been defined */ #ifdef DEBUG #define DLOG(x) (printf(x)) #else #define DLOG(x) #endif Norm...

The most common uses of #include preprocessing directives are as in the following: #include <stdio.h> #include "myheader.h" #include replaces the statement with the contents of the file referred to. Angle brackets (<>) refer to header files installed on the system, while q...

Use String initializers for converting numbers into strings: String(1635999) // returns "1635999" String(1635999, radix: 10) // returns "1635999" String(1635999, radix: 2) // returns "110001111011010011111&...

The searched CASE returns results when a boolean expression is TRUE. (This differs from the simple case, which can only check for equivalency with an input.) SELECT Id, ItemId, Price, CASE WHEN Price < 10 THEN 'CHEAP' WHEN Price < 20 THEN 'AFFORDABLE' ELSE 'EXPENSIVE' E...

Indexes can have several characteristics that can be set either at creation, or by altering existing indexes. CREATE CLUSTERED INDEX ix_clust_employee_id ON Employees(EmployeeId, Email); The above SQL statement creates a new clustered index on Employees. Clustered indexes are indexes that dict...

UPDATE Customers SET Email = "[email protected]" WHERE id = 1; This will fail if an unique index is set on the Email column of Customers. However, alternate behavior can be defined for this case: UPDATE Customers SET Email = "[email protected]" WHERE id = 1 ON DUP...

You define a class like this: class Dog {} A class can also be a subclass of another class: class Animal {} class Dog: Animal {} In this example, Animal could also be a protocol that Dog conforms to.

The Spinner can be reskinned according to your own style requirements using a Nine Patch. As an example, see this Nine Patch: As you can see, it has 3 extremely small areas of stretching marked. The top border has only left of the icon marked. That indicates that I want the left side (complete ...

Factorials can be computed at compile-time using template metaprogramming techniques. #include <iostream> template<unsigned int n> struct factorial { enum { value = n * factorial<n - 1>::value }; }; template<> struct factorial<0> { ...

WScript.Echo "Hello world!" This displays a message on the console if run with cscript.exe (the console host) or in a message box if run with wscript.exe (the GUI host). If you're using VBScript as the server-side scripting language for a web page (for classic ASP, for example), Respo...

Composer generates a vendor/autoload.php file. You might simply include this file and you will get autoloading for free. require __DIR__ . '/vendor/autoload.php'; This makes working with third-party dependencies very easy. You can also add your own code to the Autoloader by adding an autoload ...

The Implicit Grant flow is best suited for Web applications. It's easily integrated into a website using JavaScript and doesn't require a server to store the authorization code to retrieve a token. You'll first send the user to the Twitch authorization endpoint. This URL is made up of a the base au...

INSERT INTO Customers VALUES ('Zack', 'Smith', '[email protected]', '7049989942', 'EMAIL'); This statement will insert a new row into the Customers table. Note that a value was not specified for the Id column, as it will be added automatically. However, all other column values must be specified. ...

INSERT INTO Customers (FName, LName, Email, PreferredContact) VALUES ('Zack', 'Smith', '[email protected]', 'EMAIL'); This statement will insert a new row into the Customers table. Data will only be inserted into the columns specified - note that no value was provided for the PhoneNumber column. ...

The second step to creating a subscription for a user is to create and execute a billing agreement, based on an existing activated billing plan. This example assumes that you have already gone through and activated a billing plan in the previous example, and have an ID for that billing plan to refer...