一個非常簡單的Ruby case語句求解器

Question

我試圖寫入一個小程序，將計算非常簡單的方程

Revenue = Costs * (1 + Profitpercentage) 

例如，121 = 110 *（1 + 0.10），當任何一個 - 只有3個元素中的一個缺失。

我想出了：

puts "What is your Revenue ?" 
inputRevenue = gets 
puts "What are your Costs ?" 
inputCosts = gets 
puts "What is your Profit percentage ?" 
inputProfitpercentage = gets 

revenue = inputRevenue.to_f 
costs = inputCosts.to_f 
profitpercentage = inputProfitpercentage.to_f 

case 
     when (revenue == nil) then 
     puts "Your Revenue is : #{costs * (1 + profitpercentage)}"  
     when (costs == nil) then 
     puts "Your Costs are : #{revenue/(1 + profitpercentage)}" 
     else (profitpercentage == nil) 
     puts "Your Profit percentage is : #{(revenue/costs) - 1}" 
end 

要指定要計算的元素，我直接跳過了答案（我只鍵入回車）。

它與Profitpercentage未知。

隨着Costs未知它給：

你的利潤百分比是：無限

隨着Revenue未知它給：

你的利潤百分比爲：-1.0

我哪裏錯了？ （此外，它很笨拙......）

Answer 1

你不應該使用nil。只需將nil替換爲0即可。

這裏你應該做的，它會爲你工作：

puts "What is your Revenue ?" 
inputRevenue = gets 
puts "What are your Costs ?" 
inputCosts = gets 
puts "What is your Profit percentage ?" 
inputProfitpercentage = gets 

revenue = inputRevenue.to_f 
costs = inputCosts.to_f 
profitpercentage = inputProfitpercentage.to_f 

case 
     when (revenue == 0) then 
     puts "Your Revenue is : #{costs * (1 + profitpercentage)}"  
     when (costs == 0) then 
     puts "Your Costs are : #{revenue/(1 + profitpercentage)}" 
     else (profitpercentage == 0) 
     puts "Your Profit percentage is : #{(revenue/costs) - 1}" 
end 

Answer 2

input = [] 
puts "What is your Revenue ?" 
input << gets.chomp  # get rid of carriage returns 
puts "What are your Costs ?" 
input << gets.chomp 
puts "What is your Profit percentage ?" 
input << gets.chomp 

input.map! do |rcp| 
    rcp.strip.empty? ? nil : rcp.to_f 
end 

case 
    when input[0].nil? 
    puts "Your Revenue is : #{input[1] * (1 + input[2])}"  
    when input[1].nil? 
    puts "Your Costs are : #{input[0]/(1 + input[2])}" 
    when input[2].nil? 
    puts "Your Profit percentage is : #{(input[0]/input[1]) - 1}" 
    else 
    puts "Oooups. Entered everything." 
end