Ruby basic2

Ruby Basic (2)Author: Jason

Content

Method

Regular Expression

Block

Iterator

Convention

Method

No type in parameter since Ruby is dynamic

last expression value will be returned

But You can explicitly state the return statement

Method Example

def say_goodnight(name)

"Good night, " + name

end

say_goodnight("jason") # => "Good night, jason"

return

Common method

Method Usage

print print content with no line break

puts print content with line break

p same as puts but more detailed

Regular Expression

Ruby is built in with Regular Expression

Regular Expression is also a class in Ruby

patten = /Perl|Python/

patten.class # => Regexp

Find with Regex

Use =~ to find that String contains pattern or not

line = "Perl"

if line =~ /Perl|Python/

puts "line contain Perl or Python"

end

Substitution with Regex

line = "Perl, Perl , Perl"

sub : substitute first occurrence

line.sub(/Perl/,"Ruby") # => "Ruby, Perl , Perl"

gsub: substitute all occurrence

line.gsub(/Perl/,"Ruby") # => "Ruby, Ruby , Ruby"

Block

You may consider block as a anonymous function called by another method

By Convention:

Single expression inside block use {}

Many expressions inside block use do..end

Block Example

Single expression

{ puts "hello" }

Many expressions

do

puts "hello"

puts "world"

end

Called by function?def greet

yield

puts "Jason"

end

greet { puts "Hi" }

Result:

Hi

Jason

code in {} will be placed in yield

Block with argument

def greet

yield("Jason")

end

greet { |name| puts "Hello, #{name}" }

Result: Hello, Jason

PS: It does’t matter what your variable name is inside |..|

"Jason" become name

Iterator

Many iterator can take a block

Iterator can help you loop though an array and do some operations

A basic iterator is .each which loop all of the element in the array

Iterator Examplenames = %w{jason sam ray}

names.each do |name|

print "Weclome, "

puts name

end

Result:

Weclome, jason

Weclome, sam

Weclome, ray

Convention