From: Brian Candler <B.Candler@...>
Date: 2007-02-12T22:53:44+09:00
Subject: Re: embedding if statements in upto function.(newbie question)

> With this I get an error on the 3rd line of undefined method(-) for ".08 
> #(the first number)#":String(NoMethodError)Print was able to do the 
> calculation without the if statements.

I expect the problem is that a[x][y] contains a string, not an integer.

You can confirm this by adding

    puts a.inspect

into your program just after you've read in the array, and look for
["0", "1", "2"] instead of [0, 1, 2]

To fix the problem, try adding some .to_i calls on the elements before
performing the arithmetic on them.

irb(main):001:0> a = "9"
=> "9"
irb(main):002:0> b = "6"
=> "6"
irb(main):003:0> a - b
NoMethodError: undefined method -' for "9":String
        from (irb):3
irb(main):004:0> a.to_i - b.to_i
=> 3

Notice that the problem you have come across has nothing to with "if"
statements, nor with them being embedded in the "upto" construct. The moral:
try to avoid premature diagnosis :-)

Regards,

Brian.