Simple problem with Regular Expression

[Max Norman]

This simple application is an extension of an exercise from Peter
Cooper's 'Beginning Ruby, from Novice to Professional.' Its purpose is
simple: to collect the name of a fruit and print a sentence describing
the fruits name and its color. I've just learned of regular expressions,
so I've introduced an 'if' statement that modifies the sentence to suit
a name that begins with a vowel, replacing 'a' with 'an.' Unfortunately,
this feature doesn't seem to work. The program prints the sentence, but
doesn't change it if the word begins with a vowel.

Here is the code:
fruit = gets.chomp.downcase

if fruit == "orange"
color = "orange"
elsif fruit == "apple"
color = "green"
elsif fruit == "banana"
color = "yellow"
else
color = "unknown"
end

fruit.scan(/^./) do |first|
if first == 'a' || first == 'e' || first = 'i' || first = 'o' || first
= 'u'
puts "An #{fruit} is #{color}."
else
puts "A #{fruit} is #{color}."
end
end

 

[Iñaki Baz Castillo]

El Martes, 21 de Julio de 2009, Max Norman escribi=C3=B3:

fruit.scan(/^./) do |first|

If you are using Ruby 1.9 jthen do:

fruit[0] =3D> returns the first char of fruit.

=2D-=20
I=C3=B1aki Baz Castillo <[email protected]>

 

[Iñaki Baz Castillo]

El Martes, 21 de Julio de 2009, Max Norman escribi=C3=B3:

Here is the code:
fruit =3D gets.chomp.downcase

if fruit =3D=3D "orange"
color =3D "orange"
elsif fruit =3D=3D "apple"
color =3D "green"
elsif fruit =3D=3D "banana"
color =3D "yellow"
else
color =3D "unknown"
end

fruit.scan(/^./) do |first|
if first =3D=3D 'a' || first =3D=3D 'e' || first =3D 'i' || first =3D '= o' || first
=3D 'u'
puts "An #{fruit} is #{color}."
else
puts "A #{fruit} is #{color}."
end
end

Ruby code must be beautiful:

=2D---------------------------------
fruit =3D gets.chomp.downcase

case fruit
when "orange"
color =3D "orange"
when "apple"
color =3D "green"
when "banana"
color =3D "yellow"
else
color =3D "unknown"
end

if %w{a e i o u}.include?(fruit[0])
puts "An #{fruit} is #{color}."
else
puts "A #{fruit} is #{color}."
end
=2D----------------------------------




PS: Just valid for 1.9 due to the usage of "fruit[0]".


=2D-=20
I=C3=B1aki Baz Castillo <[email protected]>

 

[Max Norman]

fruit = gets.chomp.downcase

case fruit
when "orange"
color = "orange"
when "apple"
color = "green"
when "banana"
color = "yellow"
else
color = "unknown"
end

if %w{a e i o u}.include?(fruit[0])
puts "An #{fruit} is #{color}."
else
puts "A #{fruit} is #{color}."
end

Thanks for this. I've just come across a few of these concepts, like
literal arrays, denoted by %w{}. Could you explain your usage of the
literal array?

 

[Iñaki Baz Castillo]

El Martes, 21 de Julio de 2009, Max Norman escribi=C3=B3:

fruit =3D gets.chomp.downcase

case fruit
when "orange"
color =3D "orange"
when "apple"
color =3D "green"
when "banana"
color =3D "yellow"
else
color =3D "unknown"
end

if %w{a e i o u}.include?(fruit[0])
puts "An #{fruit} is #{color}."
else
puts "A #{fruit} is #{color}."
end

Thanks for this. I've just come across a few of these concepts, like
literal arrays, denoted by %w{}. Could you explain your usage of the
literal array?

Easy:

irb> my_array =3D %w{a e i o u}
["a", "e", "i", "o", "u"]

irb> my_array
["a", "e", "i", "o", "u"]



=2D-=20
I=C3=B1aki Baz Castillo <[email protected]>

 

[Max Norman]

PS: Just valid for 1.9 due to the usage of "fruit[0]".

Unfortunately I'm not using 1.9, but I would appreciate any explanation
of this syntax as well. Are you referring to the word 'fruit' as an
array, then specifying the first element of that array?

How would one code this in 1.8?

 

[Caleb Clausen]

Ruby code must be beautiful:

----------------------------------
fruit =3D gets.chomp.downcase

case fruit
when "orange"
color =3D "orange"
when "apple"
color =3D "green"
when "banana"
color =3D "yellow"
else
color =3D "unknown"
end

if %w{a e i o u}.include?(fruit[0])
puts "An #{fruit} is #{color}."
else
puts "A #{fruit} is #{color}."
end
-----------------------------------




PS: Just valid for 1.9 due to the usage of "fruit[0]".

But, you can do better:

FRUIT2COLOR=3D{
'orange'=3D>'orange', 'apple'=3D>'red', 'banana'=3D>'yellow'
}
fruit =3D gets.chomp.downcase
color=3DFRUIT2COLOR[fruit] || 'unknown'
if /^[aeiou]/=3D=3D=3Dfruit
article=3D"An"
else
article=3D"A"
end
puts "#{article} #{fruit} is #{color}."

Works perfectly in 1.8.

PS: since this program seems to assume english input, you can also
assume ascii encoding, and therefore your version works fine in 1.8
too.

PPS: Hmm, I seem to have subconsciously repainted the apples red. I
was going to point out that apples are stereotypically red, and that
the bananas you can actually buy in the store are actually green...

 

[Iñaki Baz Castillo]

El Martes, 21 de Julio de 2009, Max Norman escribi=C3=B3:

PS: Just valid for 1.9 due to the usage of "fruit[0]".

Unfortunately I'm not using 1.9, but I would appreciate any explanation
of this syntax as well. Are you referring to the word 'fruit' as an
array, then specifying the first element of that array?

'fruit' is not an array, but a string.
However, 'fruit'[0] returns the first character of the string (note that in=
=20
Ruby a character is also a string).

How would one code this in 1.8?

fruit[/^(.)/]


=2D-=20
I=C3=B1aki Baz Castillo <[email protected]>

 

[Max Norman]

How would one code this in 1.8?

fruit[/^(.)/]

This works perfectly.