我正在尝试寻找一个函数来选择字符串的前100个字符。在PHP中,存在substr function
Ruby有类似的功能吗?
发布于 2011-06-21 18:43:26
尝试foo[0...100]
,任何范围都可以。范围也可以变为负数。它是Ruby的well explained in the documentation。
发布于 2016-01-24 17:46:57
使用[]
-operator (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!)
Update for Ruby 2.7:Beginless ranges现在在这里(截至2019-12-25),可能是“返回数组的第一个xx”的标准答案:
foo[...100] # Get all chars from the beginning up until the 100th (exclusive)
使用.slice
方法(docs):
foo.slice(0, 100) # Get 100 characters starting at position 0
foo.slice(0...100) # Behaves the same as operator []
为了完整性:
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
Update for Ruby 2.6:Endless ranges现在就在这里(截至2018-12-25)!
foo[0..] # Get all chars starting at the first. Identical to foo[0..-1]
foo[-100..] # Get the last 100 characters
https://stackoverflow.com/questions/6423966
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