set serveroutput on
DECLARE
message constant varchar2(32767):= 'Hello, World!';
BEGIN
dbms_output.put_line(message);
END;
/
Command set serveroutput on is required in SQL*Plus and SQL Developer clients to enable the output of dbms_output. Without the command nothing is displayed.
T...
Django handles a request by routing the incoming URL path to a view function. The view function is responsible for returning a response back to the client making the request. Different URLs are usually handled by different view functions. To route the request to a specific view function, Django look...
A simple hello world grammar can be found here:
// define a grammar called Hello
grammar Hello;
r : 'hello' ID;
ID : [a-z]+ ;
WS : [ \t\r\n]+ -> skip ;
To build this .g4 sample you can run the following command from your operating systems terminal/command-line:
Java -jar antlr-4.5.3-...
foldMap maps each element of the Foldable structure to a Monoid, and then combines them into a single value.
foldMap and foldr can be defined in terms of one another, which means that instances of Foldable need only give a definition for one of them.
class Foldable t where
foldMap :: Monoid m...
As parameters (float, double)
Floats are 32 bits in size, they are passed naturally on the stack.
Doubles are 64 bits in size, they are passed, on the stack, respecting the Little Endian convention1,
pushing first the upper 32 bits and than the lower ones.
//C prototype of callee
double foo(dou...
The clear property is directly related to floats.
Property Values:
none - Default. Allows floating elements on both sides
left - No floating elements allowed on the left side
right - No floating elements allowed on the right side
both - No floating elements allowed on either the left or the r...
This is a very common workflow when using Ansible for provisioning an AWS EC2 instance. This post assumes a basic understand of Ansible and most importantly, assumes you've properly configured it to connect to AWS.
As Ansible official documentation insists, we are going to use four roles:
1- ami_f...
Managing AWS resources that scale up and down runs into the limits of the static inventory host file, that's why we need something dynamic. And that's what the dynamic inventories are for. Let's start:
Download these ec2.ini and ec2.py files to the your project folder:
cd my_ansible_project
wget...
There is a maximum capacity an integer can store. And when you go over that limit, it will loop back to the negative side. For int, it is 2147483647
int x = int.MaxValue; //MaxValue is 2147483647
x = unchecked(x + 1); //make operation explicitly unchecked so that the ...
Overflow also happens during the operation. In the following example, x is an int, 1 is an int by default. Therefore addition is an int addition. And the result will be an int. And it will overflow.
int x = int.MaxValue; //MaxValue is 2147483647
long y = x + 1; //...
If you are using multiple namespaces that may have same-name classes(such as System.Random and UnityEngine.Random), you can use an alias to specify that Random comes from one or the other without having to use the entire namespace in the call.
For instance:
using UnityEngine;
using System;
Ran...
Over time, our classes may implement more and more interfaces. When these interfaces have many methods, the total number of methods in our class will become very large.
For example, let's suppose that we have two interfaces and a class implementing them:
interface Printable {
public functio...
To install an APK file, use the following command:
adb install path/to/apk/file.apk
or if the app is existing and we want to reinstall
adb install -r path/to/apk/file.apk
To uninstall an application, we have to specify its package
adb uninstall application.package.name
Use the following...
file is no longer a builtin name in 3.x (open still works).
Internal details of file I/O have been moved to the standard library io module, which is also the new home of StringIO:
import io
assert io.open is open # the builtin is an alias
buffer = io.StringIO()
buffer.write('hello, ') # returns...
import cv2
image_path= #put your image path here
#use imread() function to read image data to variable img.
img = cv2.imread(image_path)
#display image data in a new window with title 'I am an image display window'
cv2.imshow('I am an image display window',img)
#wait until user hi...
Java Logging Api has 7 levels. The levels in descending order are:
SEVERE (highest value)
WARNING
INFO
CONFIG
FINE
FINER
FINEST (lowest value)
The default level is INFO (but this depends on the system and used a virtual machine).
Note:
There are also levels OFF (can be used to turn log...
The reserved word "void" is an alias of System.Void type, and has two uses:
Declare a method that doesn't have a return value:
public void DoSomething()
{
// Do some work, don't return any value to the caller.
}
A method with a return type of void can still have the return ...
