Getting Started with Ruby (scripting language for object-oriented programming)

Ruby is a scripting language for simple and fast object -Oriented programming (object-oriented programming).

Simple Introduction

• Ruby is open source and available on the web for free, but requires a license .
• Ruby is a universal, interpreted programming language .
• Ruby is a true object-oriented programming language.
• Ruby is a server-side scripting language similar to Python and Perl.
• Ruby can be used to write generic Gateway Interface (CGI) scripts.
• Ruby can be embedded in Hypertext Markup Language (HTML).
• Ruby syntax is simple, which makes it possible for new developers to learn ruby at high speed and ease.
• Ruby has a similar syntax to many programming languages such as C + + and Perl.
• Ruby is extensible, and large programs written in Ruby are easy to maintain.
• Ruby can be used to develop Internet and Intranet applications.
• Ruby can be installed in Windows and POSIX environments.
• Ruby supports many GUI tools, such as TCL/TK, GTK, and OpenGL.
• Ruby can be very easy to connect to DB2, MySQL, Oracle, and Sybase.
• Ruby has a rich built-in function that can be used directly from a ruby script.

features

Completely object-oriented, in the Ruby language, no matter what is the object, contains the basic data types in other languages, for example, the integer variable has no type, ruby variables can be saved regardless of the type of data.    No matter what has a value, whether it is a numeric or logical expression or a statement, there is a value.    The Ruby language is so elegant that it can be read without staring. Ruby is a dynamic language, and you can change previously defined classes in your program, and classes that have already been defined can be changed at execution time. It is also possible to define a method specific to that instance in an instance of a class, which is called a singleton method.

Grammar

The keyword in Ruby are as follows:

Modules Definition: module

Class definition: Class

Method definition: Def,undef

Check type: Defined?

Conditional statement: if,then,else,elsif,case,when,unless

Looping statements: For,in,while,until,next,break,do,redo,retry,yield

Logical inference: Not,and,or

Logical value: True,false

Null value: Nil

Exception handling: Rescue,ensure

Object reference: Super,self

Start of block: Begin/end

Embedded module: Begin,end

File Related: __file__,__line__

method returns: Return

Aliases: Alias

Note: The Begin module is equivalent to a macro in the C language, and the end module is used for some finishing work. With require,include, the syntax definition for begin and end should be canceled.

The operators in Ruby include the following: priority (from high to low)

[], []= array subscript, array element assignment  

* * Ride the Underworld

！ , ~, +,- non, bit non, unary plus (positive), minus

*,/,% multiply, divide, die

+,- add, subtract

>>, << right shift, left shift

& Bit and

^, | bit XOR, bit, or

<=, <, >, >= less than or equal, less than, greater than, greater than or equal to

<=>, = =, = =, =~,! =,!~ Various equality inferences (cannot rewrite =~,! =,!~)

&& Short Circuit and

|| Short Circuit or

..、... start point of interval to end point

? : ternary conditional operator

=,%=, ~=,/=,-=, + =, |=, &=, >>=, <<=, *=, &&=, | | =, **= various assignments

Defined? Check Type

not logical non-

Or, and logical OR, logical and

If, unless, while, until inference and looping

Begin, end define method, class, scope of module

Attention:

It is important to note that Ruby does not have "+ +", "--" operators, but can be implemented by "+=1", "-=1".

Some conventions for Ruby identifiers:

Local variables start with lowercase letters or underscores

Global variables begin with a dollar sign.

Instance variable starts with @

Class variables start with @@

A constant or class name begins with an uppercase letter.

The Nilkeyword in Ruby are very special. Nil represents a concept of an empty set that is similar to null in other languages. and other languages do not, Ruby in the logical inference process, only nul and false is false, all other expressions are true.

Methods in Ruby

Write amethod in Ruby now and write a simple hello

defSay_hello (name)

result= "Hello," +name

returnresult

End

Puts Say_hello ("oec2003")#返回hello, oec2003

The way to see Ruby is to use the KEYWORDDEF definition followed by the method name, end With end, accustomed to C # and Java, may feel uncomfortable very accustomed. In the inner statement of the method, it is assumed that each statement is placed on a separate line, with no semicolon appended to the statement.

Classes in Ruby

the same classes in Ruby are defined as Keywordclass, followed by theclass name

Class Oec2003

End

Classes typically inherit the base base class in Rails

Class Oec2003<activerecord::base

End

Indicates that Oec2003 inherits the base base class, and the inheritance in Ruby is implemented with <, and the base base class belongs to the module ActiveRecord

Methods in the Ruby class can be added to the access modifier to limit the level of the interview

Class Oec2003

Def method1 #No plus no matter what modifier, feel public

     End

     Protected

     Def method2 #Modifier is proteted, note that the modifier is written on top of the method

 end

    private

    def method3

    end

end

、

Private

defmethod3

End

End

Modules in Ruby

modules and classes are a bit similar, they all include a set of methods, constants and other classes and module definitions, unlike classes where modules cannot createinstances.

There are two uses for the module. First: The function of the namespace, so that the name of the method will not conflict. Second: The ability to share the same functionality among different classes. Assuming a class is mixed with a module, the class has all of the instance methods in the module, as if it were defined in the class

ModuleOec2003

End

Control structures in Ruby

Conditional Inference statement: Infer whether equality is used = = in the condition, and be careful not to write =

Ifcount>10

puts" countgreater than 10"

elsif count==10#Note here is elsif instead of elseif

puts "Count equals10"

Else

puts "count less than10"

End

Loop statement:

While loop

Whileage<30

putsage

age=+1

End

Single-line while

Age=age+1 while age<30

Until cycle

A=1

Until a>=10

puts a

A+=1

End

For: In.. Cycle

For I in 1..9

puts I,""

End

Getting Started with Ruby (scripting language for object-oriented programming)