Nested arrays - what can be wrong with this?

[Tim L]

Can anyone explain why this code:

a = Array.new(3,Array.new(3,0))
a[1][1]=1
a.each {|r| puts r.join(', ')}

generates this output?

0, 1, 0
0, 1, 0
0, 1, 0

I was expecting this

0, 0, 0
0, 1, 0
0, 0, 0

Something wrong with my understanding of Ruby - or conceivably the set up on
my PC?

Tim L

 

[Daniel Schierbeck]

Can anyone explain why this code:

a = Array.new(3,Array.new(3,0))
a[1][1]=1
a.each {|r| puts r.join(', ')}

generates this output?

0, 1, 0
0, 1, 0
0, 1, 0

Try this:

ary = Array.new(3){Array.new(3, 0)}


Cheers,
Daniel

 

[marek4130]

Hi Tim,

The Array.new(3,0) is called only once. so a has 3 references to the
same array.
a[0] == a[1] will return true as will a[1] == a[2]

Instead try:
a = Array.new(3) {Array.new(3,0)}

have fun,
Marek

 

[Tim L]

Thank you guys

Hi Tim,

The Array.new(3,0) is called only once. so a has 3 references to the
same array.
a[0] == a[1] will return true as will a[1] == a[2]

Instead try:
a = Array.new(3) {Array.new(3,0)}

have fun,
Marek

Can anyone explain why this code:

a = Array.new(3,Array.new(3,0))
a[1][1]=1
a.each {|r| puts r.join(', ')}

generates this output?

0, 1, 0
0, 1, 0
0, 1, 0

I was expecting this

0, 0, 0
0, 1, 0
0, 0, 0

Something wrong with my understanding of Ruby - or conceivably the set up
on
my PC?

Tim L