sTinGe / RubyTrails

RubyTrails

Here are some trails for Ruby, please leave your feedback if you want.

01. I/O stream

print "Hello, World!"

print a string

name = gets.chomp

get string from input stream

name.capitalize!

Modified name by converting the first character to uppercase and the reminder to lowercase, return nil if no changed.

 name.capitalize

Return a "copy" of name with the first character convert to uppercase and the reminder to lowercase.

puts line

print a line

02. Flow Control

if num < 0 
	puts "You picked a negative integer!"
elsif num > 0
	puts "You pick a positive integer!"
else
	puts "You picked zero!"
end

The if keyword is used to check if an expression is true.

If it is true, a statement is then executed.

print "Enter domain:"
domain = gets.chomp
domain.downcase
case domain
	when "us"
		puts "United States"
	when "uk"
		puts "United Kingdom"
	else
		puts "Unknown"
end

case just like switch in c, but more powerful and simplier.

i = 0
loop = 0
while i < 10 do
	i = i+1
	loop = loop+i 
end

while is also simple, don't forget do and end.

left = 12
until left == 0 
	if left == 1
		puts "There is only #{left} seconds left"
	else 
		puts "There are #{left} seconds left"
	end 
	left -= 1
end

until is a special and semantic statement in ruby, the thing you should notice that the statement followed by until is false compared to until conditional statement.

planets = ["Mercury", "Venus", "Earth", 
"Mars", "Jupiter", "Saturn", "Uranus", "Neptune"]
planets.each do |planet|
	puts planet
end

In the traversal of array, each is a better method than for, it could rapidly visit elements in arrays.

03. Substitute

substitute is a useful method for changing characters in strings.

print "Thtring pleathe!: "
user_input = gets.chomp
user_input.downcase!

if user_input.include? "s"
	user_input.gsub!(/s/, "th")
else
	puts "Nothing to do here!"
end

puts "Your string is: #{user_input}" 

include? method check the substring whether in string or not.

gsub! changes the character and replace origin.

Of course, more useful method could do more things, in ruby, method is a powerful tool to make your code be better, be more performance.

##04. Hash & Symbol