2013IT鐵人賽-13-ruby03-練習Learn Ruby The Hard Way網站範例

2013IT鐵人賽-13-ruby03-練習Learn Ruby The Hard Way網站範例

這次我們的讀書會選用的是Oreilly 的Ruby程式設計這本書, 然後建議的練習是採用”笨方法學 Ruby” http://lrthw.github.io/ 上面的範例.

所以今天就來練習網站上面的範例吧 :-)

本次練習還是使用 EasyCloud 的 VM 來練習, 並連接終端機來操作.

首先先建立工作目錄吧(我的 git 工作目錄在 /root 目錄下面, 請依造自己的設定來調整)

# cd  /root

# mkdir  ruby/Lab-LRTHW

首先來練習 習題1: 第一個程式

建立一個檔案 ex1.rb 於我們剛剛建立好的Lab-LRTHW目錄下, 內容如下

# cat   ruby/Lab-LRTHW/ex1.rb

# puts 的相關練習

puts "Hello World!"

puts "Hello Again"

puts "I like typing this."

puts "This is fun."

puts "Yay! Printing"

puts "I'd much rather you 'not'."

#這邊透過單引號 ' ' 來讓雙引號顯示於螢幕上面, 單引號內一律視為字串

puts 'I "said" do not touch this.'

並使用 ruby 指令執行該程式

# ruby   ruby/Lab-LRTHW/ex1.rb

Hello World!

Hello Again

I like typing this.

This is fun.

Yay! Printing

I'd much rather you 'not'.

I "said" do not touch this.

接下來練習 習題 2: 註釋和井號

建立一個檔案 ex2.rb 於我們剛剛建立好的Lab-LRTHW目錄下, 內容如下

# cat   ruby/Lab-LRTHW/ex2.rb

# A comment, this is so you can read your program later.

# Anything after the # is ignored by Ruby.

# 註解是用來看程式的說明的, 在#符號後面的字元都會被 Ruby 忽略

puts "I could have code like this."# and the comment after is ignored 這段文字會被忽略

# You can also use a comment to "disable" or comment out a piece of code:

# print "This won't run."

# 你也可以使用註解來停用某些程式碼

puts "This will run."

並使用 ruby 指令執行該程式

# ruby   ruby/Lab-LRTHW/ex2.rb

I could have code like this.

This will run.

接下來練習 習題 3: 數字和數學計算

建立一個檔案 ex3.rb 於我們剛剛建立好的Lab-LRTHW目錄下, 內容如下

# cat   ruby/Lab-LRTHW/ex3.rb

# 數字和數學計算

puts "I will now count my chickens"

=begin

這邊會先印出 Hens 然後換行

顯示 30 => 因為是 25 + 5 (30/6)的結果 / 除法的優先性大於+加法

=end

puts "Hens", 25 + 30 / 6

=begin

這邊會先印出 Roosters 然後換行

顯示 97 => 100 - 3 (75 / 4 的餘數)的結果,

75 為 25*3 的結果, %為求出餘數, 故 75 除以 4 為 18 餘 3.

=end

puts "Roosters", 100 - 25 * 3 % 4

puts "Now I will count the eggs:"

=begin

這邊會顯示 7 => 3 + 2 + 1 - 5 + 0 - 0 + 6

4 % 2 => 0 餘數為 0 這個部份比較沒有爭議

1 / 4 => 0 這邊其實要注意的是因為沒有宣告為浮點數, 所以只會當成整數來處理, 所以 1 / 4 => 0.25 因為是整數, 所以值為0

=end

puts 3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6

# 利用一個小範例來顯示 1/4 的結果

print "print 1/4 result: "

puts 1/4

puts "Is it true that 3 + 2 < 5 - 7?"

# 因為有 < 符號, 所以會判斷 5 < -2 是否為真

# 故顯示 false

puts 3 + 2 < 5 - 7

puts "What is 3 + 2?", 3 + 2

puts "What is 5 - 7?", 5 - 7

puts "Oh, that's why it's false."

puts "How about some more."

# 這邊是進行邏輯判斷, 我認為把運算式寫入字串顯示會比較好

puts "Is it greater? 5 > -2", 5 > -2

puts "Is it greater or equal? 5 >= -2", 5 >= -2

puts "Is it less or equal? 5 <= -2", 5 <= -2

並使用 ruby 指令執行該程式

# ruby   ruby/Lab-LRTHW/ex3.rb

I will now count my chickens

Hens

30

Roosters

97

Now I will count the eggs:

7

print 1/4 result: 0

Is it true that 3 + 2 < 5 - 7?

false

What is 3 + 2?

5

What is 5 - 7?

-2

Oh, that's why it's false.

How about some more.

Is it greater? 5 > -2

true

Is it greater or equal? 5 >= -2

true

Is it less or equal? 5 <= -2

false

最後加入到 git  並傳送到 GitHub

# git  add ruby/*

# git  commit  -m "Lab and exercise Learn Ruby The Hard Way ex1.rb to ex3.rb"

[master e510744] Lab and exercise Learn Ruby The Hard Way ex1.rb to ex3.rb

3 files changed, 66 insertions(+)

create mode 100644 ruby/Lab-LRTHW/ex1.rb

create mode 100644 ruby/Lab-LRTHW/ex2.rb

create mode 100644 ruby/Lab-LRTHW/ex3.rb

# git push  origin  master

Username for 'https://github.com': 您的帳號

Password for 'https://sakanamax@github.com': 您的密碼

Counting objects: 9, done.

Compressing objects: 100% (7/7), done.

Writing objects: 100% (7/7), 1.78 KiB, done.

Total 7 (delta 1), reused 0 (delta 0)

To https://github.com/sakanamax/2013ironman.git

  abde303..e510744  master -> master

Fun with Day 13 ~