Tbpgr Blog

Ruby プログラマ tbpgr(てぃーびー) のブログ

Ruby | String | []

概要

String#self[nth] -> String | nil
String#slice(nth) -> String | nil
String#self[nth, len] -> String | nil
String#slice(nth, len) -> String | nil

詳細

nth 番目の文字を返却。

nth が正の場合: 文字列の先頭から数える
nth が負の場合: 文字列の末尾から数える
nth が範囲外の場合: nil を返却

サンプルコード
require 'tbpgr_utils'


bulk_puts_eval binding, <<-EOS
"123456789"[0]
"123456789"[3]
"123456789"[-1]
"123456789"[-3]
"123456789"[0, 3]
"123456789"[3, 3]
"123456789"[-1, 3]
"123456789"[-3, 3]
"123456789"[10]
"-------------------------------"
"123456789".slice(0)
"123456789".slice(3)
"123456789".slice(-1)
"123456789".slice(-3)
"123456789".slice(0, 3)
"123456789".slice(3, 3)
"123456789".slice(-1, 3)
"123456789".slice(-3, 3)
"123456789".slice(10)
EOS

__END__
下記はTbpgrUtils gemの機能
bulk_puts_eval

https://rubygems.org/gems/tbpgr_utils
https://github.com/tbpgr/tbpgr_utils

出力

"123456789"[0]                    # => "1"
"123456789"[3]                    # => "4"
"123456789"[-1]                   # => "9"
"123456789"[-3]                   # => "7"
"123456789"[0, 3]                 # => "123"
"123456789"[3, 3]                 # => "456"
"123456789"[-1, 3]                # => "9"
"123456789"[-3, 3]                # => "789"
"123456789"[10]                   # => nil
"-------------------------------" # => "-------------------------------"
"123456789".slice(0)              # => "1"
"123456789".slice(3)              # => "4"
"123456789".slice(-1)             # => "9"
"123456789".slice(-3)             # => "7"
"123456789".slice(0, 3)           # => "123"
"123456789".slice(3, 3)           # => "456"
"123456789".slice(-1, 3)          # => "9"
"123456789".slice(-3, 3)          # => "789"
"123456789".slice(10)             # => nil