How to input integer value to an array, based preceeding row + column values? [duplicate]

Answer 1

You've accidentally posted this twice. Here is the answer I gave on the other copy:

The method you are looking for is the =~ operator. If you use it on a string and give it a regexp pattern it will return the location of that pattern in the string. Thus:

x = 'R1C2C3-5'

x =~ /R/

returns: 0 since that is the position of 'R' in the string (counted just like an array 0,1,2...).

If you are unfamiliar with regexp and the =~ operator, I suggest you check out the Ruby doc on it, it is very valuable. Basically the pattern between the forward slashes get matched. You are looking to match + or -, but they have special meaning in regexp, so you have to escape them with a backslash.

x =~ /\+/
x =~ /\-/

but you can combine those into one pattern matcher with an OR symbol (pipe) |

x =~ /\+|\-/

So now you have a method to get the operator:

def operator(my_string)
  r = my_string.slice(my_string =~ /\+|\-/)
end

I would also use the operator to split your string into the column/row part and the numeric part:

op = operator(x)    # which returns op = '-'
arr = x.split(my_string(x))  # which returns an array of two strings ['R1C2C3', '5']

I leave further string manipulation up to you. I would read through this page on the String class: Ruby String Class and this on arrays: Ruby Array Class as Ruby contains so many methods to make things like this easier. One thing I've learned to do with Ruby is think "I want to do this, I wonder if there is already a built in method to do this?" and I go check the docs. Even more so with Rails!

Answer 2

Your homework, sir.

puts 'Please input: '
x = gets.chomp

col = []
row = []
sign = ''
val = ''

x.chars.each_slice(2) do |u|
  case u[0]
  when 'R' then
    row << u[1]
  when 'C' then
    col << u[1]
  when '+', '-'
    sign, val = u[0], u[1]
  else
    puts 'Invalid input.'
    exit
  end
end

big_row = row.max.to_i
big_col = col.max.to_i
table = Array.new (big_row) { Array.new(big_col) }

# Initialize table to all zeros
table.map! do |row|
  row.map! { |col| 0 }
end

rows_range = row.length == 1 ? row[0]..row[0] : row[0]..row[1]
cols_range = col.length == 1 ? col[0]..col[0] : col[0]..col[1]

table.each_with_index do |row, ri|
  if rows_range.include? (ri + 1).to_s
    row.each_with_index do |col, ci|
      if cols_range.include? (ci + 1).to_s
        table[ri][ci] = (sign + val).to_i
      end
    end
  end
end

# Padding for fields in table.
padding = 4

# Table
table.each do |row|
  row.each do |col|
    print "#{col.to_s.rjust(padding)}"
  end
  print "\n"
end