Ruby: passing array items into a case statement

问题

I am attempting to pass an array into a case statement so I can read the array elements as commands. Unfortunately, it seems that it is not working and the program jumps to the else statement.

def input_console()
            quit = 0

    puts "Tell me what you want to do:"

    loop do

        print "\n >>> "
        input = gets.chomp
        sentence = input.split

        case sentence
            when sentence[0] == "go" && sentence[1] == "to"
                puts sentence[2]
            when sentence[0] == "quit"
                quit = 1
            else
                puts "No le entiendo Senor..."
        end
        break if quit == 1
    end
end

This piece of code returns "No le entiendo Senor..." whatever you introduce. I expected to get the place I want to go after stating "go to Wherever".

Please, ¿may you help me?

回答1:

You can do this by making your case statement independent of a specific variable.

change

case sentence

case

回答2:

Here is an example of how you would use case-when while checking for values in the array.

numbers = [1,2,3]
case 
when a[1] == 2
  p "two"
else
  p "nothing"
end

So in your case you can just say

case
when sentence[0] == "go" && sentence[1] == "to"
  puts sentence[2]
when sentence[0] == "quit"
  quit = 1
else
  puts "No le entiendo Senor..."  
end

回答3:

Why are you making this a case statement? (And why is quit a Fixnum rather than a boolean? Actually, why have it at all?)

while true
    # ... prompt and get input ...
    if sentence[0] == "go" && sentence[1] == "to"
        puts sentence[2]
    elsif sentence[0] == "quit"
        break
    else
        puts "No le entiendo Senor..."
    end
end

回答4:

You could use regular expressions. Something like this:

case gets
when /\Ago to (.*)\Z/
  puts $1
when /\Aquit\Z/
  # handle quit
else
  puts "No le entiendo Senor..."
end

\A matches the beginning of string and \Z matches just before the trailing newline, so you don't need chomp.

来源：https://stackoverflow.com/questions/20006056/ruby-passing-array-items-into-a-case-statement

标签

ruby

arrays

case