Tutorial by Examples: b

Linux has a command for almost any tasks and most of them are intuitive and easily interpreted. Getting Help in Linux CommandUsabilityman <name>Read the manual page of <name>.man <section> <name>Read the manual page of <name>, related to the given section.man -k <e...

The observer pattern lets users of a class subscribe to events that happen when this class processes data etc. and be notified when these event occur. In the following example we create a processing class and an observer class which will be notified while processing a phrase - if it finds words that...

Corner radius for all 4 edges: UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRoundedRect: CGRectMake(x,y,width,height) cornerRadius: 11]; [UIColor.grayColor setFill]; [rectanglePath fill]; Corner radius for top-left edge: UIBezierPath* rectanglePath = [UIBezierPath bezierPat...

For a simple circle: UIBezierPath* ovalPath = [UIBezierPath bezierPathWithOvalInRect: CGRectMake(0,0,50,50)]; [UIColor.grayColor setFill]; [ovalPath fill]; Swift: let ovalPath = UIBezierPath(ovalInRect: CGRect(x: 0, y: 0, width: 50, height: 50)) UIColor.grayColor().setFill() ovalPath.fill...

For bezier path to get resized based on the view frame, override the drawRect of view that you are drawing the bezier path : - (void)drawRect:(CGRect)frame { UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: CGRectMake(CGRectGetMinX(frame), CGRectGetMinY(frame), CGRectGetWidth(f...

Consider a simple rectangle that is drawn by the bezier path. UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: CGRectMake(x,y,width,height)]; [UIColor.grayColor setFill]; [rectanglePath fill]; Basic Outer-fill shadow: CGContextRef context = UIGraphicsGetCurrentContext();...

In C, all function parameters are passed by value, so modifying what is passed in callee functions won't affect caller functions' local variables. #include <stdio.h> void modify(int v) { printf("modify 1: %d\n", v); /* 0 is printed */ v = 42; printf("modify 2:...

class A: x = None # type: float def __init__(self, x: float) -> None: """ self should not be annotated init should be annotated to return None """ self.x = x @classmethod def from_int(cls, x: int...

Variables are annotated using comments: x = 3 # type: int x = negate(x) x = 'a type-checker might catch this error' Python 3.x3.6 Starting from Python 3.6, there is also new syntax for variable annotations. The code above might use the form x: int = 3 Unlike with comments, it is also pos...

Double quoteSingle quoteAllows variable expansionPrevents variable expansionAllows history expansion if enabledPrevents history expansionAllows command substitutionPrevents command substitution* and @ can have special meaning* and @ are always literalsCan contain both single quote or double quoteSin...

x = 5 x += 7 for x in iterable: pass Each of the above statements is a binding occurrence - x become bound to the object denoted by 5. If this statement appears inside a function, then x will be function-local by default. See the "Syntax" section for a list of binding statements. ...

You can force deallocate objects even if their refcount isn't 0 in both Python 2 and 3. Both versions use the ctypes module to do so. WARNING: doing this will leave your Python environment unstable and prone to crashing without a traceback! Using this method could also introduce security problems ...

User Prompts are methods part of the Web Application API used to invoke Browser modals requesting a user action such as confirmation or input. window.alert(message) Show a modal popup with a message to the user. Requires the user to click [OK] to dismiss. alert("Hello World"); More...

Using the dataset property The new dataset property allows access (for both reading and writing) to all data attributes data-* on any element. <p>Countries:</p> <ul> <li id="C1" onclick="showDetails(this)" data-id="US" data-dial-code="1&q...

The code below will prompt for numbers and continue to add them to the beginning of a linked list. /* This program will demonstrate inserting a node at the beginning of a linked list */ #include <stdio.h> #include <stdlib.h> struct Node { int data; struct Node* next; }; ...

const int a = 0; /* This variable is "unmodifiable", the compiler should throw an error when this variable is changed */ int b = 0; /* This variable is modifiable */ b += 10; /* Changes the value of 'b' */ a += 10; /* Throws a compiler error */ The const qualif...

If while working you realize you're on wrong branch and you haven't created any commits yet, you can easily move your work to correct branch using stashing: git stash git checkout correct-branch git stash pop Remember git stash pop will apply the last stash and delete it from the stash list. T...

Here we make a simple echo websocket using asyncio. We define coroutines for connecting to a server and sending/receiving messages. The communcations of the websocket are run in a main coroutine, which is run by an event loop. This example is modified from a prior post. import asyncio import ai...

Using vanilla mathematics: var from:Point = new Point(100, 50); var to:Point = new Point(80, 95); var angle:Number = Math.atan2(to.y - from.y, to.x - from.x); Using a new vector representing the difference between the first two: var difference:Point = to.subtract(from); var angle:Number ...

Using vanilla mathematics: var from:Point = new Point(300, 10); var to:Point = new Point(75, 40); var a:Number = to.x - from.x; var b:Number = to.y - from.y; var distance:Number = Math.sqrt(a * a + b * b); Using inbuilt functionality of Point: var distance:Number = to.subtract(from).len...