From: Roger Bannister <rdb@...>
Date: 2004-04-27T09:14:14+09:00
Subject: The Strangeness of Arrays

Hi

The behaviour below has me completely confuzzled. Why on earth does my 
array suddenly have all rows equal to the last row?

Can anyone tell me if this is expected; or if I have to start wearing my 
Stupid Hat again.

Thanks
R

irb(main):014:0> @t = Array.new(5, Array.new(4))
=> [[nil, nil, nil, nil], [nil, nil, nil, nil], [nil, nil, nil, nil], 
[nil, nil, nil, nil], [nil, nil, nil, nil]]
irb(main):025:0> row = 0
=> 0
irb(main):026:0> while (row <= 4)
irb(main):027:1> column = 0
irb(main):028:1> while (column <= 3)
irb(main):029:2> printf(".%d,%d: %d. ", column, row, @t[row][column] = 
row+column)
irb(main):030:2> column += 1
irb(main):031:2> end
irb(main):032:1> printf("\n")
irb(main):033:1> row += 1
irb(main):034:1> end
.0,0: 0. .1,0: 1. .2,0: 2. .3,0: 3.
.0,1: 1. .1,1: 2. .2,1: 3. .3,1: 4.
.0,2: 2. .1,2: 3. .2,2: 4. .3,2: 5.
.0,3: 3. .1,3: 4. .2,3: 5. .3,3: 6.
.0,4: 4. .1,4: 5. .2,4: 6. .3,4: 7.
=> nil
irb(main):035:0> @t
=> [[4, 5, 6, 7], [4, 5, 6, 7], [4, 5, 6, 7], [4, 5, 6, 7], [4, 5, 6, 7]]