Ruby小笔记
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逻辑或运算符作用,判断空值的语法糖
a=nil
a||=333 则 a=333
inject的语法糖
inject(initial, sym) → obj inject(sym) → obj inject(initial) {| memo, obj | block } → obj inject {| memo, obj | block }
例如 (5..10).inject(1,:+) 与 (5..10).inject(1) {|sum,n| sum+n}
ruby gem 不下载rdoc ri
vim ~/.gemrc
gem: --no-ri --no-rdoc
ruby的正则表达式
http://rubular.com/
[abc]
A single character: a, b or c[^abc]
Any single character but a, b, or c[a-z]
Any single character in the range a-z[a-zA-Z]
Any single character in the range a-z or A-Z^
Start of line$
End of line\A
Start of string\z
End of string.
Any single character\s
Any whitespace character\S
Any non-whitespace character\d
Any digit\D
Any non-digit\w
Any word character (letter, number, underscore)\W
Any non-word character\b
Any word boundary character(...)
Capture everything enclosed(a|b)
a or ba?
Zero or one of aa*
Zero or more of aa+
One or more of aa{3}
Exactly 3 of aa{3,}
3 or more of aa{3,6}
Between 3 and 6 of a
- 类似awk的文本处理,命令行方式
awk参考 http://www.cnblogs.com/chengmo/archive/2010/10/06/1844818.html 和 man awk cat /etc/passwd |awk -F: '/root/{print $1}' 或者
awk -F: '/root/{print $1}' /etc/passwd
ruby实现
cat /etc/passwd |grep root |ruby -F: -ane 'puts $F[0]'
注意要使用$类预定义变量,用双引号的时候,需要使用#{$_}计算变量值
cat /etc/passwd |grep root|ruby -ne 'a=$_.match(/\d+/);puts "#{$.} #{a} #{$_}" '
- Rubygem出现“too many connection resets ”错误
gem install 出现:删除用户目录下的.gem目录,以及gem的各种cache
push gem 出现:http://help.rubygems.org/discussions/problems/715-too-many-connection-resets
- Ruby正则表达式一特殊语法
a = "hello there"
a[/[aeiou](.)\1/, 1] #=> "l"
- *的匹配
一般来说*用于把一个array展开:
a, *b = [1,2,3] #a = 1, b = [2,3]
引用 http://www.iteye.com/topic/24642
逻辑或运算符作用,判断空值的语法糖
a=nil
a||=333 则 a=333
inject的语法糖
inject(initial, sym) → obj inject(sym) → obj inject(initial) {| memo, obj | block } → obj inject {| memo, obj | block }
例如 (5..10).inject(1,:+) 与 (5..10).inject(1) {|sum,n| sum+n}
ruby gem 不下载rdoc ri
vim ~/.gemrc
gem: --no-ri --no-rdoc
ruby的正则表达式
http://rubular.com/
[abc]
A single character: a, b or c[^abc]
Any single character but a, b, or c[a-z]
Any single character in the range a-z[a-zA-Z]
Any single character in the range a-z or A-Z^
Start of line$
End of line\A
Start of string\z
End of string.
Any single character\s
Any whitespace character\S
Any non-whitespace character\d
Any digit\D
Any non-digit\w
Any word character (letter, number, underscore)\W
Any non-word character\b
Any word boundary character(...)
Capture everything enclosed(a|b)
a or ba?
Zero or one of aa*
Zero or more of aa+
One or more of aa{3}
Exactly 3 of aa{3,}
3 or more of aa{3,6}
Between 3 and 6 of a
- Rubygem出现“too many connection resets ”错误
gem install 出现:删除用户目录下的.gem目录,以及gem的各种cache
push gem 出现:http://help.rubygems.org/discussions/problems/715-too-many-connection-resets
- Ruby正则表达式一特殊语法
a = "hello there"
a[/[aeiou](.)\1/, 1] #=> "l"
- *的匹配
- 一般来说*用于把一个array展开:
a, *b = [1,2,3] #a = 1, b = [2,3]
引用 http://www.iteye.com/topic/24642
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