Tutorial by Examples: b

You should use this when you have two text fields that should receive exactly the same content. For example, you may want to confirm an email address or a password. This validation creates a virtual attribute whose name is the name of the field that has to be confirmed with _confirmation appended. ...

When using Autolayout with a UIScrollView, it does NOT resize properly depending on the size of its contents or subviews. In order to get a UIScrollView to automatically scroll when its contents become too large to fit in the visible area, we need to add a ContentView and some constraints that allo...

The simplest way to get an event handler called on a key press is to connect the handler to the key-press-event signal. In this example, we register for the event for the whole window, but you can also register for individual widgets too. The most important part is the connection of the handler to ...

A StringBuilder represents a series of characters, which unlike a normal string, are mutable. Often times there is a need to modify strings that we've already made, but the standard string object is not mutable. This means that each time a string is modified, a new string object needs to be created,...

Short circuiting is a functionality that skips evaluating parts of a (if/while/...) condition when able. In case of a logical operation on two operands, the first operand is evaluated (to true or false) and if there is a verdict (i.e first operand is false when using &&, first operand is tr...

library(gpuR) # gpuMatrix objects X <- gpuMatrix(rnorm(100), 10, 10) Y <- gpuMatrix(rnorm(100), 10, 10) # transfer data to GPU when operation called # automatically copied back to CPU Z <- X %*% Y

library(gpuR) # vclMatrix objects X <- vclMatrix(rnorm(100), 10, 10) Y <- vclMatrix(rnorm(100), 10, 10) # data always on GPU # no data transfer Z <- X %*% Y

From MSDN Use the CInt function to provide conversions from any other data type to an Integer subtype. For example, CInt forces integer arithmetic when currency, single-precision, or double-precision arithmetic would normally occur. Assuming that you have 1 button and 2 textbox. If you type...

In most cases, it is illegal to access an object of one type as though it were a different type (disregarding cv-qualifiers). Example: float x = 42; int y = reinterpret_cast<int&>(x); The result is undefined behavior. There are some exceptions to this strict aliasing rule: An obj...

Consider writing a "hello world!" program in c. Lets say our source code is in a file called source.c, now in order to run our program we need to compile it, typically on Linux (using gcc) we would need to type $> gcc source.c -o output where output is the name of the executable to be g...

The ProcessBuilder class makes it easy to send a command through the command line. All it requires is a List of Strings that make up the commands to be entered. You simply call the start() method on your ProcessBuilder instance to execute the command. If you have a program called Add.exe which take...

In general when making a call to the command line, the program will send the command and then continue its execution. However you may want to wait for the called program to finish before continuing your own execution (ex. The called program will write data to a file and your program needs that to a...

Launching external processes from Java using the raw java.lang.ProcessBuilder API directly can be a little cumbersome. The Apache Commons Exec library makes it a little easier. The ch.vorburger.exec library further extends upon Commons Exec to make it truly convenient: ManagedProcess proc = new ...

Get current time: Time.now Time.new # is equivalent if used with no parameters Get specific time: Time.new(2010, 3, 10) #10 March 2010 (Midnight) Time.new(2015, 5, 3, 10, 14) #10:14 AM on 3 May 2015 Time.new(2050, "May", 3, 21, 8, 16, "+10:00") #09:08:16 PM on 3 May 2050...

DATA: <TABLE NAME> TYPE <SORTED|STANDARD|HASHED> TABLE OF <TYPE NAME> WITH <UNIQUE|NON-UNIQUE> KEY <FIELDS FOR KEY>. Standard Table This table has all of the entries stored in a linear fashion and records are accessed in a linear way. For large table sizes, ...

Notice, this is only for angular-cli up to 1.0.0-beta.10 version ! Some libraries or plugins may not have typings. Without these, TypeScript can't type check them and therefore causes compilation errors. These libraries can still be used but differently than imported modules. Include a scr...

For example: ActiveRecord::Base.transaction do david.withdrawal(100) mary.deposit(100) end This example will only take money from David and give it to Mary if neither withdrawal nor deposit raise an exception. Exceptions will force a ROLLBACK that returns the database to the state before ...

A transaction acts on a single database connection. If you have multiple class-specific databases, the transaction will not protect interaction among them. One workaround is to begin a transaction on each class whose models you alter: Student.transaction do Course.transaction do course.enro...

There are two types of callbacks associated with committing and rolling back transactions: after_commit and after_rollback. after_commit callbacks are called on every record saved or destroyed within a transaction immediately after the transaction is committed. after_rollback callbacks are called o...

ActiveRecord::Base.transaction uses the ActiveRecord::Rollback exception to distinguish a deliberate rollback from other exceptional situations. Normally, raising an exception will cause the .transaction method to rollback the database transaction and pass on the exception. But if you raise an Activ...