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...
This example will call the windows calculator. It's important to notice that the exit code will vary accordingly to the program/script that is being called.
package process.example;
import java.io.IOException;
public class App {
public static void main(String[] args) {
try {
...
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...
Though the transaction class method is called on some ActiveRecord class, the objects within the transaction block need not all be instances of that class. This is because transactions are per-database connection, not per-model.
In this example a balance record is transactionally saved even though ...
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...
Both #save and #destroy come wrapped in a transaction that ensures that whatever you do in validations or callbacks will happen under its protected cover. So you can use validations to check for values that the transaction depends on or you can raise exceptions in the callbacks to rollback, includin...
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...
Built-in functionals: lapply(), sapply(), and mapply()
R comes with built-in functionals, of which perhaps the most well-known are the apply family of functions. Here is a description of some of the most common apply functions:
lapply() = takes a list as an argument and applies the specified ...
User-defined functionals
Users can create their own functionals to varying degrees of complexity. The following examples are from Functionals by Hadley Wickham:
randomise <- function(f) f(runif(1e3))
lapply2 <- function(x, f, ...) {
out <- vector("list", length(x...
To print a test field (TestField) from a test feature class (TestFC) in a test file geodatabase (Test.gdb) located in a temporary folder (C:\Temp):
with arcpy.da.SearchCursor(r"C:\Temp\Test.gdb\TestFC",["TestField"]) as cursor:
for row in cursor:
print row[0]
When either a signed or unsigned integer is converted to a signed integer type, and its value is not representable in the destination type, the value produced is implementation-defined. Example:
// Suppose that on this implementation, the range of signed char is -128 to +127 and
// the range of un...
Here is a simple JsonArray which you would like to convert to a Java ArrayList:
{
"list": [
"Test_String_1",
"Test_String_2"
]
}
Now pass the JsonArray 'list' to the following method which returns a corresponding...
Sometimes in a development or testing environment, the SSL certificate chain might not have been fully established (yet).
To continue developing and testing, you can turn off SSL verification programmatically by installing an "all-trusting" trust manager:
try {
// Create a trust mana...
Config values can be set in three ways:
Via private static variables on any class within a SilverStripe project
Via yaml config files (stored in module-folder/_config/[file].yml)
Via PHP at run time (Config::inst()->update('Director', 'environment_type', 'dev')
Generally it's best to se...
Emacs uses the terms point, mark, and region to provide more precision about the selected text and position of the cursor. By understanding these terms, it'll help you understand and use other operations and functions.
The point is the place in a buffer where editing (i.e. insertion) is currently t...
Download
Use Firebird site to download the correct "server package" for your system.
First, select the version of Firebird that you would like to install.
Next, select the appropriated installer for your system. Example, for almost any version of Windows 32 bits, you would select under ...
