紅寶石變量不會增加或減少

Question

我試圖號碼添加到一個變量，然後顯示變量，但是變量只是保持不變:(下面的代碼...

cash = 50 
puts "You have #{cash} dollars" 
sleep (2) 
cash + 5 
puts "You have #{cash} dollars" 

它只是顯示了50依舊。有人可以幫忙嗎？

Answer 1

把它寫成cash = cash + 5，您將獲得所需的輸出。cash + 5創造了新的Fixnum例如55，但你沒有對象55的參考分配回本地變量cash。看下面：

cash = 50 
puts "You have #{cash} dollars" 
sleep(2) # or you can write as sleep 2 
cash = cash + 5 
puts "You have #{cash} dollars" 
# >> You have 50 dollars 
# >> You have 55 dollars 

現在，如果你不想cash = cash + 5做什麼，如下圖所示：

cash = 50 
puts "You have #{cash} dollars" 
sleep(2) # or you can write as sleep 2 
puts "You have #{cash+5} dollars" 
# >> You have 50 dollars 
# >> You have 55 dollars 

Answer 2

就其本身而言，只有cash + 5輸出的評價 - 在你的情況，你想分配輸出到cash：

cash = 50      # Declare the `cash` variable 
#=> 50 

puts "You have #{cash} dollars" # Print the value of `cash` 
#=> You have 50 dollars 

cash + 5      # Print the value of (`cash` + 5) WITHOUT assigning it 
#=> 55 

puts "You have #{cash} dollars" # Print the value of `cash` 
#=> You have 50 dollars 

cash = cash + 5     # Assign the returned value of (`cash` + 5) to `cash` 
#=> 55 

puts "You have #{cash} dollars" # Print the value of `cash` 
#=> You have 55 dollars 

Answer 3

cash = 50 
puts "You have #{cash} dollars" 
sleep (2) 
cash + 5 # this just returns 55 in ruby. For example you could have newVar = cash + 5 , newVar would equal 55 but cash still would equal 50 
puts "You have #{cash} dollars" 

爲了得到您想要的金額，請執行以下操作。 每次添加到變量最常用的方法是這樣的

cash += 5 

這是簡寫

cash = cash + 5 

Answer 4

cash + 5 

在上面的代碼中你總結5到現金，但結果是丟棄。實際上，右側沒有任何分配。

cash = cash + 5 

將產生期望的結果。在這種情況下，您還可以使用shortand

cash += 5