私は選択するための関数を見つけようとしています文字列の最初の100文字。 PHPには、substrfunction が存在します
Rubyには同様の機能がありますか?
foo[0...100]
、どの範囲でもかまいません。範囲は負になることもあります。これは ドキュメントで詳しく説明されています Rubyです。
[]
- operatorの使用( docs ):
foo[0, 100] # Get 100 characters starting at position 0
foo[0..99] # Get all characters in index range 0 to 99 (inclusive!)
foo[0...100] # Get all characters in index range 0 to 100 (exclusive!)
.slice
メソッドの使用( docs ):
foo.slice(0, 100) # Get 100 characters starting at position 0
foo.slice(0...100) # Behaves the same as operator []
完全を期すために:
foo[0] # Returns the indexed character, the first in this case
foo[-100, 100] # Get 100 characters starting at position -100
# Negative indices are counted from the end of the string/array
# Caution: Negative indices are 1-based, the last element is -1
foo[-100..-1] # Get the last 100 characters in order
foo[-1..-100] # Get the last 100 characters in reverse order
foo[-100...foo.length] # No index for one beyond last character
Ruby 2.6 :の更新: 無限の範囲 はここにあります(2018-12-25現在)!
foo[0..] # Get all chars starting at the first. Identical to foo[0..-1]
foo[-100..] # Get the last 100 characters