Question

在用户未输入else或1的{{1}}处，脚本应在显示错误消息后重新开始。我怎么能这样做？

Answer 1

您需要包装整个事件in a while loop并将变量input初始化为类似nil的值。

while循环的条件应该检查值是1还是2，并且可能需要转换为.to_i的整数，因为gets将返回一个字符串。< / p>

# initialize to nil
input = nil

# Check if the current value (integer) is 1 or 2
while !([1,2].include?(input))
  puts "Do you want to calculate celcius to fahrenheit (1) or fahrenheit to celcius(2)"

  # Convert the string to an int after getting it as input
  input = gets.to_i

  if input == 1
    puts "Please enter degrees in Celcius."
    celcius = gets
    fahrenheit = (celcius.to_i * 9 / 5) + 32
    print "The result is "
    print fahrenheit
    puts "."
  # elsif here, not elseif!!
  elsif input == 2
      puts "Please enter degrees in Fahrenheit."
      fahrenheit = gets
      celcius = (fahrenheit.to_i / 9 * 5) - 32
      print "The result is:"
      print celcius
      puts "."
  else
      puts "Please enter option 1 or 2"
  end
end

事实上，在测试负面条件时，使用while循环（Ruby与许多其他语言不同）而不是until循环更具可读性：

until [1,2].include?(input)
  ...
end

[1,2].include?(input)是一种更为流畅的写作方式

 if input == 1 || input == 2

...可以轻松扩展数组中的其他值。

Answer 2

这是使用功能。

puts "Do you want to calculate celcius to fahrenheit (1) or fahrenheit to celcius(2)"
def convert
    input = gets
    if input == 1
        puts "Please enter degrees in Celcius."
        celcius = gets
        fahrenheit = (celcius.to_i * 9 / 5) + 32
        print "The result is "
        print fahrenheit
        puts "."
    elseif input == 2
        puts "Please enter degrees in Fahrenheit."
        fahrenheit = gets
        celcius = (fahrenheit.to_i / 9 * 5) - 32
        print "The result is:"
        print celcius
        puts "."
    else
        puts "Please enter option 1 or 2"
        convert()
    end
end

如果输入！=（2 || 1）也可以。

if / else再次启动该功能

2 个答案: