Terry July Ruby Reading Notes (more detailed) page 1/4

Page 3Overview

Description and execution: Python and Ruby are highly interactive; ○ Compilation and execution: Pascal, C, fast. N local execution, such as C, C ++; N virtual machine execution, such as Java, C #.   ○ Dynamic languages, such as JavaScript and Ruby; ○ Static languages, such as C ++ and Java.

 

Language ○ Syntax Keywords Description ○ Pragmatic

Matz 1993

Ruby ['ru: bi] (Ruby)

 

 

Ruby draws on perl regular expressions, python's simplicity and readability, smalltalk's pure object-oriented syntax and single inheritance, LISP's infinitely nested syntax, Java's thread...

 

Page 14Getting started

XP

Cmd

C: \ Documents ents and Settings \ Administrator> ruby-v Ruby 1.8.6 (patchlevel 111) [i386-mswin32]

 

Method 1:RubyCommand

C: \ Documents ents and Settings \ Administrator> ruby-e 'print "hello world "' Hello world

 

Ruby runs ruby;

-E: Execute the subsequent ruby script program;

Print display;

Hello, world.

 

Method 2:IrbInteractive execution

C: \ Documents ents and Settings \ Administrator> irb Irb (main): 001: 0> print "hello world" Hello world => nil Irb (main): 002: 0> exit

 

Exit: exit the irb interactive environment.

 

Method 3: CreateRubyScript

C: \ Documents ents and Settings \ Administrator> copy con helloworld. rb Print "hello world" Print "3*7 =", 3*7 ^ Z Copied 1Files.   C: \ Documents ents and Settings \ Administrator> helloworld. rb Hello world3 * 7 = 21

 

Page 17IDE

○ Eclipse + RDT (Ruby Development Tools)

○ FreeRIDE + SciTE

1. Edit Ruby code in SciTE;

2. Save. RbFile;

3. In the menu bar, choose tools> RUN or F5;

Page 18Syntax

1.Note

Single line comment # multi-line comment = begin = end

Ruby embedded document (Rdoc) annotation, using the ri command to generate documents from the source file.

Rdoc is embedded in ruby code and can be converted to html documents.

Ri command to view the function description and class description. Function Description and class description should be placed in = begin and = end. Note: "= begin" must be written at the beginning of the line. That is to say, the first six characters in this line are "= begin". spaces are not allowed before.

2.Branch

The statement ends with a semicolon.

Multiple statements in one row are separated by semicolons. The last statement can be omitted. A line break indicates that a row ends.

The statement is too long. You can use the '\' symbol at the end of the line to represent the continued row.

3.Delimiter

Name	Symbol	Purpose
Semicolon	;	Used to separate multiple statements in a row
Parentheses	()	Raise the priority; include the parameter list when defining a method
Space		Delimiter; In the case where () can be omitted, replace ()
Comma	,	Separate multiple parameters
Point	.	Separate an object from its Method
Two colons	::	The domain identifier that separates a module (class) from its constants.

4.Keywords

The keywords in Ruby are as follows:

Module definition:	Module	Exception Handling:	Rescue, ensure
Class Definition:	Class	Object Reference:	Super, self
Method definition:	Def, undef	Block start:	Begin/end
Check type:	Defined?	Embedded Module:	BEGIN, END
Logical value and null value:	True, false, nil	File-related:	_ FILE __,__ LINE __
Logical judgment:	Not, and, or	Method return:	Return
Condition Statement:	If, then, else, elsif, case, when, unless	Alias:	Alias
Loop statement:	For, in, while, until, next, break, do, redo, retry, yield

The BEGIN module is equivalent to a macro in the C language, and the END module is used for some final work. With

Require, include, should cancel the syntax definition of BEGIN and END.

5.Operator

6.Identification name:

Constants, variables, methods, classes, and modules;

Case Sensitive;

The first character indicates the usage of the name.

Local variables, method parameters, and method names	It must start with a lowercase letter or underscore;
Class Name, Module name, and constant	It must start with an uppercase letter.
Global Variables	Prefix with the dollar sign $;
Instance variables	Starting;
Class variable	Start;

The first letter can be followed by any combination of letters, numbers, and underscores;

@ Cannot be followed by numbers directly.

Ruby program code is represented by a 7-bit acⅱ code, which supports eight-bit coding systems such as EUC, SJIS, and UTF-8 through language extensions. Ruby2.0 supports 16-bit Unicode encoding.

7.Class Library

You can directly use:

I) KEYWORDS;

Ii) classes and methods in the require or include class libraries;

Iii) methods inherited from the parent class.

 

Puts	Automatic line feed after each parameter
Print	Do not automatically wrap, use "\ n" for line feed"
Printf	Output by format, not automatically wrap
Gets	Read data from the keyboard or file

 

C: \ Documents ents and Settings \ Administrator> ruby-e 'puts "hello", "world "' Hello World

 

C: \ Documents ents and Settings \ Administrator> ruby-e 'printf "number: % f", 100' No.: 3.200000

 

 

Note: printf parameters are separated by commas.

C: \ Documents ents and Settings \ Administrator> ruby-e 'printf "number: % 4.3f, string % s ", 1.5," hello world "' Number: 1.500, string hello world

 

8.Data Type

Type	Category	Description and example
Number	Integer	0 octal, 0x hexadecimal, 0b binary
	Floating Point Type
String	Single quotes''
	Double quotation mark ""
Array	Starting from 0, each element can be of different types	Example [2.4, "thank you", [a, B, c], 78]
Interval	1. 5	1, 2, 3, 4, 5
	1... 5	1, 2, 3, 4
Regular Expression

9.Value assignment

Values of the exchange variables a and B:

A, B = B,;

Note:

A = (B = 1 + 2) + 3 # a = 6, B = 3

Comma (,), from left to right, assigned to a, B, and c respectively.

X = 0 # x = 0

A, B, c = x, (x + 1), (x + 2) # a = 0, B = 1, c = 2

10.Conditional operation

=	Equal	! =	Not equal
Eql?	Compare the values and types of the two objects.	Equal?	Compare whether two objects have the same address in the memory
<	Less	>	Greater
<=	Less than or equal	> =	Greater than or equal
= ~	Match Regular Expression	!~	Assertion does not match the Regular Expression
===	The object on the right is within the left range. Puts (0 .. 9) ===3.14 # true puts ('A'... 'F') ==='c' # true	<=>	Compare the sizes of two objects, greater than 1, equal to 0, less than-1.

In Ruby, nil and false are false, while others are true.

 

11.Judgment statement

Single line if statement	If then end
	() If
Multi-line if statement	If elsif else end
Unless Condition Statement	Unless
	If not
Case branch Condition Statement	Case When When Else End

 

12.Loop statement

Single Row while	(Statement 1; Statement 2; statement ...) While Condition
Multiline while	While Condition Statement End
Until	Until jump out of the loop Condition Statement Until condition = while not (condition)
For... In Loop	For variable in object Statement 1; Statement 2; statement... End

 

Break, next & redo & retry

In the circular body, if you encounter:

Break	Jump out of the current layer loop;
Next	Ignore the remaining part of this loop and start the next loop;
Redo	Start the loop again, or start from this time;
Retry	Start the loop body.

 

Times, upto, downto, each, step

Statement	Running result
3. times {print "Hi! "}	# Hi! Hi! Hi!
1. upto (9) {| I | print I if I <7}	#123456
9. downto (1) {| I | print I if I <7}	#654321
(1 .. 9). each {| I | print I if I <7}	#123456
0. step (11,3) {| I | print I}	#0369

 

C: \ Documents ents and Settings \ Administrator> irb Irb (main): 001: 0> 1. upto (9) {| I | print I if I <7} 123456 => 1 Irb (main): 002: 0> 9. downto (1) {| I | print I if I <7} 654321 => 9 Irb (main): 003: 0> (1 .. 9). each {| I | print I if I <7} 123456 => 1 .. 9 Irb (main): 004: 0> 0. step (11,3) {| I | print I} 0369 => 0

 

13. Exception

Java

Try... Catch... Finally... Throw

Ruby

Begin/end... Rescue... Ensure... Raise

Retry can be used in rescue. You can only use rescue or ensure. when both are used, rescue must be before ensure.

14. threads