Ruby if語句多個條件不等

Question

我不明白爲什麼多個if語句條件與不等於不起作用。在irb

2.3.0 :009 > H = Hash["a" => 100, "b" => 200, "c" => 1000, "d" => 2000] 
=> {"a"=>100, "b"=>200, "c"=>1000, "d"=>2000} 
2.3.0 :011 > H.each do |key, v| 
2.3.0 :012 >  if (key != "a") || (key != "b") 
2.3.0 :013?>  puts key 
2.3.0 :014?>  end 
2.3.0 :015?> end 
a 
b 
c 
d 
=> {"a"=>100, "b"=>200, "c"=>1000, "d"=>2000} 
2.3.0 :016 > H.each do |key, v| 
2.3.0 :017 >  if key != "a" || key != "b" 
2.3.0 :018?>  puts key 
2.3.0 :019?>  end 
2.3.0 :020?> end 
a 
b 
c 
d 
=> {"a"=>100, "b"=>200, "c"=>1000, "d"=>2000} 
2.3.0 :021 > H.each do |key, v| 
2.3.0 :022 >  if !(key == "a") || !(key == "b") 
2.3.0 :023?>  puts key 
2.3.0 :024?>  end 
2.3.0 :025?> end 
a 
b 
c 
d 
=> {"a"=>100, "b"=>200, "c"=>1000, "d"=>2000} 

但這個工程：

2.3.0 :026 > H.each do |key, v| 
2.3.0 :027 >  if (key == "a") || (key == "b") 
2.3.0 :028?>  puts key 
2.3.0 :029?>  end 
2.3.0 :030?> end 
a 
b 
=> {"a"=>100, "b"=>200, "c"=>1000, "d"=>2000} 

缺少什麼我在這裏？

Answer 1

我想你想實現什麼，可以做副

H.each do |key, v| 
    if (key != "a") && (key != "b") 
    puts key 
    end 
end 

注 - 如果有兩個條件是真||運營商將返回true。

希望有所幫助。

Answer 2

的

if (key == "a") || (key == "b") 

逆實際上是

if !(key == "a") && !(key == "b") 

如果你說「它可以是這樣或那樣的」相反的是「它不可能是這一點，並不能說」