查找兩個數組之間共同的值

Question

如果我想比較兩個數組並創建一個插值輸出字符串，如果y數組變量存在於x中我怎樣才能得到每個匹配元素的輸出？

這是我正在嘗試，但沒有得到結果。

x = [1, 2, 4] 
y = [5, 2, 4] 
x.each do |num| 
    puts " The number #{num} is in the array" if x.include?(y.each) 
end #=> [1, 2, 4] 

Answer 1

您可以使用交集方法&爲：

x = [1, 2, 4] 
y = [5, 2, 4] 
x & y # => [2, 4] 

Answer 2

x = [1, 2, 4] 
y = [5, 2, 4] 
intersection = (x & y) 
num = intersection.length 
puts "There are #{num} numbers common in both arrays. Numbers are #{intersection}" 

將輸出：

There are 2 numbers common in both arrays. Numbers are [2, 4] 

Answer 3

OK，所以&運營商似乎是唯一你需要做得到這個答案。

但在此之前，我知道，我寫了一個快速的猴子補丁的數組類要做到這一點：

class Array 
    def self.shared(a1, a2) 
    utf = a1 - a2 #utf stands for 'unique to first', i.e. unique to a1 set (not in a2) 
    a1 - utf 
    end 
end 

的&操作是正確的答案，但。更優雅。