The C in Ruby

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# The `%%` in Ruby

.b[[@abelar_s](https://twitter.com/abelar_s) -
[@ParisRB](https://twitter.com/parisrb) -
[@RailsGirlsParis](https://twitter.com/railsgirlsparis)]
 
[maitre-du-monde.fr](maitre-du-monde.fr)

.contrib[[Contribute to this talk on GitHub!](https://github.com/abelards/abelards.github.com/edit/master/talks/C_in_Ruby.html)]

???

---
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# Strings
```
'Hello %s' % 'world'
# => "Hello world!"
```

---
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# c for Character
```
%c % 'Hello'
# => ArgumentError: %c requires a character

%c % 'A'
# => 'A'
```

---
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# p for inspect (print)

```ruby
Membre = Struct.new(:nom, :prenom)
m = Membre.new('Abélard', 'Sylvain')

'%p' % m
# => "#<struct Membre nom=\"Abélard\", prenom=\"Sylvain\">"
```

---
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# Alignments
```
'% 8s' % 'Test.'
# => "   Test."

'%-8s' % 'Test.'
# => "Test.   "
```

---
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# Several args
```
"%s. %s %s est %i%% fan de Ruby." %
  ['M', 'Sylvain', 'Abélard', 100]
# => "M. Sylvain Abélard est 100% fan de Ruby."
```

---
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# Several args
```
civ, nom, prenom, pourcent =
  ['M', 'Sylvain', 'Abélard', 100]

"%s. %s %s est %i%% fan de Ruby." %
  civ, nom, prenom, pourcent

# => "M. Sylvain Abélard est 100% fan de Ruby."
```

---
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# Strings

```
'%{sujet} %{verbe} %{complement}' %
   {sujet: 'printf', verbe: 'formate',
	complement: 'des chaînes'}

# => "printf formate des chaînes"
```

---
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# _(GetText)

```
_('%{sujet} %{verbe} %{complement}') %
   {sujet: 'printf', verbe: _('formate'),
	complement: _('des chaînes')}

# FR => "printf formate des chaînes"
# EN => "printf formats strings"
```

---
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# Formats
```
'%d %i %u' % [1, 3.14, 0xF]
# => "1 3 15" # entier

'%o %#o' % [8, 010]
# => "10 010" # octal

'%b %#b' % [42, 0b101010]
# => "101010 0b101010" # binaire

'%x %X %#x' % [42, 0xDEADBEEF, 0xC0FFEE]
# => "2a DEADBEEF 0xc0ffee" # hexa
```

---
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# Numbers

```
tests = [1, 2048, 3.14159, -42]
tests.map {|test| pattern % test }
```

---
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# Numbers
```
'%04i' % x
# 0001
# 2048
# 0003
# -042
```

---
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# Numbers
```
'%.2f' % x
# 1.00
# 2048.00
# 3.14
# -42.00
```

---
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# Reading
<a href="http://batsov.com/articles/2013/06/27/the-elements-of-style-in-ruby-number-2-favor-sprintf-format-over-string-number-percent/">@bbatsov prefers sprintf</a>

```
'format' % [a, b, c]
sprintf('format', a, b, c)
```

<a href="http://ruby-doc.org/core-2.2.3/Kernel.html#method-i-sprintf">
http://ruby-doc.org/core-2.2.3/Kernel.html#method-i-sprintf</a>

---
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# Questions?

.b[[@abelar_s](https://twitter.com/abelar_s) -
[@ParisRB](https://twitter.com/parisrb) -
[@RailsGirlsParis](https://twitter.com/railsgirlsparis)]
 
[maitre-du-monde.fr](maitre-du-monde.fr)

.contrib[[Contribute to this talk on GitHub!](https://github.com/abelards/abelards.github.com/edit/master/talks/C_in_Ruby.html)]

---
class: center, middle, happy
# Thanks!

.b[[@abelar_s](https://twitter.com/abelar_s) -
[@ParisRB](https://twitter.com/parisrb) -
[@RailsGirlsParis](https://twitter.com/railsgirlsparis)]
 
[maitre-du-monde.fr](maitre-du-monde.fr)

.contrib[[Contribute to this talk on GitHub!](https://github.com/abelards/abelards.github.com/edit/master/talks/C_in_Ruby.html)]