Ruby：如何在代码块中使用5个主要的Find方法

Posted 2021-02-26

This shows how we can find objects inside code blocks (aka data sets).

#find / detect returns an Object or nil, it will not find all the numbers
puts "
" + "#find returns an Object or nil"
puts (1..10).find { |i| i == 5 }
 
puts "
" + "detect returns an Object or nil. Note:It only returns the first example."
puts (1..10).detect { |i| i % 3 == 0 }
puts "
" + "detect can be used to determine which other numbers are within a range"
puts (1..10).detect { |i| (1..10).include?(i * 3) }
 
 
#find_all / select returns an Array 
puts "
" + "find_all returns an Array"
puts (1..10).find_all { |i| i % 3 == 0 }
 
puts "
" + "select returns an Array.  Three numbers can be multiplied by 3 and still not exceed 10."
puts (1..10).select { |i| (1..10).include?(i * 3) }
 
# Method any? returns a Boolean
puts "
" + "any? returns a Boolean.  In other words, are there any in the set that are true?"
puts (1..10).any?  { |i| i % 3 == 0 }
 
# Method all? returns a Boolean
puts "
" + "all? returns a Boolean.  Do all the conditions meet the requirement?"
puts (1..10).all?  { |i| i % 3 == 0 }
 
# Method delete_if? returns an Array.
puts "
" + "delete_if anything is divisible by 3"
puts [*1..10].delete_if { |i| i % 3 == 0 }