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janlelis committed May 27, 2015
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title: Golfing Basics
date: 2015-05-27
tags: syntax, golf, strings

**Code Golf** is the art of writing the shortest program possible. The less bytes the better. And the competition is just ridiculously strong! Head over to [Anarchy Golf]( if you want to see more!


A good beginner's problem is printing out [Pascal's Triangle]( Spend a few days to get to **45** bytes. Spend a few *months* to get to **43** bytes!

## 10 Ruby Tricks You'll Learn by Playing Code Golf

While code golfing does not necessarily make you a better programmer, you can learn a lot about the programming language you are using. Here are some things that were new to me:

## Dirty Interpolation

String interpolation (`#{}`) is sometimes possible without using curlies:

"You can directly interpolate #@instance variables, " \
"#@@class variables, and #$global variables!"

I must admit, this can confuse newcomers, but it looks fantastic!

## Constant Assignment in Modifiers

It is perfectly legit to use assignments in conditions:

if a = 42
p a
# => 42

However, this won't work with the shorter *modifier* syntax:

p b if b = 42
# NameError: undefined local variable or method `b'...
Unless… you use constants:
p C if C = 42
# => 42
## Shebang `require`

What could possibly be shorter than:

require'json'; require 'yaml'

It's inlined command-line options:

#!ruby -rjson -ryaml

## Iterating Input Lines

Finding the shortest way to read user input is a common problem for golfers and solutions vary, depending on how to process the input. My favorite one is to iterate over the input's lines:

$<.each{|e|p e}

## Appending Output

`puts` and `p` are already good candidates to output content. However, sometimes, using `<<` on `STDOUT` is a tiny bit (or byte) more efficent:


## Regex Always Wins

This is one of the golden rules of golfing. Especially, combining the [block syntax of `gsub`]( with the [perlish regex variables]( can be very expressive!

## `String#tr`
However, it's not true - regexes do not always win. If you need to perform some simple character substitutions, [tr]( is an extremly short (and also clean) way to do so:

# ROT13 Cipher
"Vqvbflapengvp Ehol".tr'a-zA-Z','n-za-mN-ZA-M'
# => "Idiosyncratic Ruby"

## One More or Less

In some instances, you cannot use `i+1` or `i-1` without wrapping them in parenthesis. No problem, [unary complement]( to the rescue:

-~42 # => 43
~-42 # => 41

## Flexible Precedence

This is one of my favorites: Explicitely call (`.`) operators for alternative precedence semantics:

3*(2+1) #=> 9
3.*2+1 #=> 9
## Quick Quit
What's a shorter way to quit a Ruby script than the 4 bytes long `exit` method?

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