一、Ruby Introduction：
Ruby is "an interpreted scripting language for quick and easy object-oriented programming"。
1. Interpreted scripting language
-
- ability to make operating system calls directly
- powerful string operations and regular expressions
- immediate feedback during development
2. Quick and easy
-
- variable declarations are unnecessary
- variables are not typed
- memory management is automatic
3.Object oriented programming
-
- everything is an object
二、Variables & Constant ：
1.Variables
- Local variables:
–the scope of a local variable is one of proc{ ... }/loop{ ... }.def ... End/class ... End/module ... end
- Global variables:
–It can be referred to from anywhere in a program. Before initialization, a global variable has the special value nil.
- Instance variables:
–Its scope is confined to whatever object self refers to.
- Class variables:
–Same as the static member in C# language.
Note: Don’t use the Ruby keyword when define a variable.
2.Constant
Definition:
- A constant has a name starting with an uppercase character.
- Constants may be defined within Classes or Module, never in method.
- It should be assigned a value at most once.
e.g.:
class Demo
PI=3.1415
#PI=3.15214 #warning: already initialized constant PI
def hello
PI=3.1415 #wrong
end
end
demo = Demo.new
demo.hello
三、Comment
•Single line:
#(Ctrl + /)
•Multi-line
=begin
…
…
=end
四、Numeric:
- Methods:
- to_f() #Integer -> Float
- to_i() # Float -> Integer, directly delete the part of decimal, if don’t want this, you can use the round method
- round
-
n.times{|i | …}
-
from.upto(to) {|i| …}
-
from.downto(to){|i| …}
-
from. step(to, step) {|i| …}
•Additional:
a=01123 #0=> Octal
B=-0x23 #0X=> Hex
C=+0b1010 #0=> Binary
五、Range:
1.Definition:
-
- val1.. val2 #contains: val1,…, va2
- val1…val2 #contains: val1,…, val2-1
E.g.:
1..5 #contains: 1,2,3,4,5
1…5 #contains: 1,2,3,4
2.Methods:
-
- to_a() #convert to array
- Include?(targetValue)/===(targetValue) #judge whether contains the targetValue
- min()/begin()/first() #Get the minimum value
- max()/end()/last #Get the maximum value
- reject: Convert to an array and select some element whichdon’t satisfy the conditional
- select: Convert to an array and only select some element whichsatisfy the conditional
- each: Iterates over the elements and passing each in turn to the block.
e.g.
a=10..20
puts a. reject{|x| x<15}
puts
puts a. select{|x|x<15}
puts
a. each{|x| puts x}