ruby - 简单的 if else 语句单位转换

Question

我写了这段代码，但它不工作。我真的很感激帮助：

puts "Welcome to my unit conversion calculator. This calculator can convert
    between Centimeters and Inches. If you could like to convert Centimeters to Inches,    
    write: in. If you would like to convert Inches to centimeters, write: cm."

unit = gets

puts " how many of your unit would you like to convert"

a = 0.39370079

b = 2.54

unit_number = gets.to_f

if unit = cm

    (unit_number * a)

else unit = in

    (unit_number * b)
end

Answer 1

if 语句没有做你想要的。要检查是否相等，请使用==. =是赋值

if unit == cm

但你真的想要'cm'，因为它是一个字符串。您需要将其括在引号中，以让运行时知道您的意思是一个字符串：

if unit == 'cm' 

最后，您需要向用户输出转换的内容

puts unit_number * a

甚至更好

result = unit_number * a
puts "converting #{unit_number} to #{unit} is #{result}"