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).

Brief introduction

Ruby is open source and is 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 quick and easy for new developers to learn Ruby.
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 makes it easy to connect to DB2, MySQL, Oracle, and Sybase.
Ruby has a rich built-in function that you can use directly in your Ruby script.

features

Fully object-oriented, in the Ruby language, anything is an object, including basic data types in other languages, such as integer variables without types, and ruby variables can hold any type of data.    Everything has a value, whether it's a number or a logical expression or a statement. The Ruby language is elegant and can be read without the need for annotations.

Ruby's variables have certain rules, starting with $ must be global variables, starting with @ is an instance variable, and @@ 开头 with a class variable.    The constant begins with a capital letter, which is useful for command completion of a text editor, such as typing $ and the first letter under Vim, and then tapping Ctrl+p, which complements the global variables in the file as well as the associated file. Ruby is a dynamic language, and you can modify previously defined classes in your program, and classes that have already been defined can be modified at run time. You can also define a method specific to that instance in an instance of a class, which is called a singleton method. Grammar

The keywords 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 judgment: 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 are as follows: priority (from high to low)

can override

Operator

Describe

Y

[], []=

Array subscript, array element assignment

Y

* * Ride the Underworld

Y

！ , ~, +,-

Non, bit non, unary plus (positive), minus

Y

*、/、%

Multiply, divide, mold

Y

+,-

Add, Subtract

Y

>>, <<

Move right, move left

Y

&

Bit and

Y

^, |

Bit XOR, bit, or

Y

<=, <, >, >=

Less than or equal to, less than, greater than, greater than or equal

Y

<=>, = =, = =, =~,! =,!~

Various equality judgments (cannot rewrite =~,! =,!~)

N

&&

Short Circuit and

N

||

Short Circuit or

N

..、...

Start point of interval to end point

N

? :

Ternary conditional operators

N

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

Various assignment values

N

Defined?

Check type

N

Not

Logical Non-

N

Or, and

Logical OR, logical, and

N

If, unless, while, until

Judgment and circulation

N

Begin, End

Define the scope of methods, classes, modules

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 NIL keyword in Ruby is very special. Nil represents a concept of an empty set that is similar to null in other languages. As with other languages, Ruby has only nul and false for false in logical judgment, and all other expressions are true.

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