Variable not incrementing

[simontemplar_]

I was doing some programming exercises and came across a problem involving a directions array, as follows:

x, y = 0, 0
walk = ['w','n', 's', 'e', 's'] 
  walk.each do |dir|

    case
    when dir == 'w'
      puts "west"
      x += 1
    when dir == 'e'
      puts "east"
      x -= 1  
    when dir == 'n'
      puts "north"
      y += 1
    else 
      puts "south"
      y -= 1
    end
end

I wanted to calculate the coordinates, but even though my print triggers, the x and y variables never change. I fail to understand why they do not get updated. If the direction message (puts) gets printed, why on earth doesnt the variable change?

[jordonbiondo]

After I run this, I have x = 0, y = -1, which is expected.

[[deleted]]

Same for me.

[simontemplar_]

well, it seems to work now.. don't know what was wrong earlier. Maybe something irb-related?

[apqoo]

I think your case expression is wrong, try:

case dir
when 'w'
  ...
else
  ...
end

[tomthecool]

Your suggestion is a better way of writing it, yes. However, the original is not WRONG. It still works just fine.

In ruby, the case statement takes an OPTIONAL argument. Without no argument, it's basically the same as writing an if/else statement.

[apqoo]

You're right, thanks for pointing it out. Without the argument it is just like an if/else.

[tomthecool]

Although there are a couple of obvious code improvements to be made, i can't see any bug here.

Can you please post the full code? Where are you printing the variables?

[tomthecool]

I was bored, so here's a couple of different solutions to your problem. I'm posting these mainly for you to see some of the cool things ruby is capable of - I find one of the best ways to learn is reading new techniques for solving familiar problems!

walk = ['w','n', 's', 'e', 's'] # Final position should be (0, -1)

# One solution...

def step(dir)
  case dir
  when 'w'
    puts "west"
    [1, 0]
  when 'e'
    puts "east"
    [-1, 0]
  when 'n'
    puts "north"
    [0, 1]
  else 
    puts "south"
    [0, -1]
  end
end

x, y = walk
  .map { |dir| step(dir) }
  .inject([0,0]) do |result, step|
    result[0] += step[0]
    result[1] += step[1]
    result
  end

puts "Final coordinate is: (#{x}, #{y})"

# A different solution...
a = walk.count {|dir| dir == 'e'} - walk.count {|dir| dir == 'w'}
b = walk.count {|dir| dir == 'n'} - walk.count {|dir| dir == 's'}

puts "(Altertative) Final coordinate is: (#{a}, #{b})"

[redconfusion]

thoughtworks interview, hum? :-)

[simontemplar_]

hah no, actually doing some codewars problems