shafik

What is the Strict Aliasing Rule and Why do we care?

(OR Type Punning, Undefined Behavior and Alignment, Oh My!)

What is strict aliasing? First we will describe what is aliasing and then we can learn what being strict about it means.

In C and C++ aliasing has to do with what expression types we are allowed to access stored values through. In both C and C++ the standard specifies which expression types are allowed to alias which types. The compiler and optimizer are allowed to assume we follow the aliasing rules strictly, hence the term strict aliasing rule. If we attempt to access a value using a type not allowed it is classified as undefined behavior(UB). Once we have undefined behavior all bets are off, the results of our program are no longer reliable.

Unfortunately with strict aliasing violations, we will often obtain the results we expect, leaving the possibility the a future version of a compiler with a new optimization will break code we th

HendrixString

echo -e "testing \033[48;5;88mCOLOR1\033[38;208;48;5;159mCOLOR2\033[m"

The color range of a 256 color terminal consists of 4 parts, often 5, in which case you actually get 258 colors:

• Color numbers 0 to 7 are the default terminal colors, the actual RGB value of which is not standardized and can often be configured.
• Color numbers 8 to 15 are the "bright" colors. Most of the time these are a lighter shade of the color with index - 8. They are also not standardized and can often be configured. Depending on terminal and shell, they are often used instead of or in conjunction with bold font faces.
• Color numbers 16 to 231 are RGB colors. These 216 colors are defined by 6 values on each of the three RGB axes. That is, instead of values 0 - 255, each color only ranges from 0 - 5.

HendrixString

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {

	var n, f_n_1, f_n_2 = -1, 1, 1

HendrixString

man - show the doc of a command

man <commnad>

common

. = current directory
~ = home directory
$HOME = home directory
pwd = print current directory
cat <file> = print file content
cat > <file> << EOF = write output stream into a file
export VAR=VALUE = export environment variable

HendrixString

account

setup name and email
for a specific repository, navigate into it and type
git config user.name "your username"
git config user.email "foo@bar.com"
note add --global to make it global for new repositories

change your editor for commits
git config --global core.editor "pico"
get the remote repository url

HendrixString

1. download the dependencies of the project ./gradlew assemble
2. start a java gradle project gradle init --type “java-library"
3. add the gradle wrapper to the project gradle wrapper --gradle-version 2.0
4. build ./gradlew build
5. test ./gradlew test

hlissner

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Note: these instructions are for pre-Sierra MacOS. Sierra (10.12) and newer users see https://gist.github.com/gravitylow/fb595186ce6068537a6e9da6d8b5b96d by @gravitylow

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If you are getting this in gdb on OSX while trying to run a program:

alexfu

import android.graphics.Rect;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

public class EqualSpacingItemDecoration extends RecyclerView.ItemDecoration {
  private final int spacing;
  private int displayMode;

  public static final int HORIZONTAL = 0;

revolunet

Python VS ES6 syntax comparison

Python syntax here : 2.7 - online REPL

Javascript ES6 via Babel transpilation - online REPL

Imports

import math

polbins

Simple RecyclerView Divider

Simple Horizontal Divider Item Decoration for RecyclerView

    mRecyclerView.addItemDecoration(new SimpleDividerItemDecoration(
            getApplicationContext()
    	));

NOTE: Add item decoration prior to setting the adapter