Error in While Loop

[Naresh Ramaswamy]

Following is my Ruby Code Wherein I am reading an XML file.
I am afraid why my loop is not getting incremented for value of i.
Attached is the XML file for your referance.

********************************
require 'rexml/document'
require 'rio'
include REXML

$doc = Document.new File.new("script_data.xml")

$TXN = XPath.match($doc, "//TXN[@value]")

$i = 0

def check
@a = $TXN.size
while $i <= @a #|| $TXN[@i] != 0 do
loop_1
@b = $TXN[$i].size
@j=1
while @j <= @b || $TXN[$i][@j] != nil do
loop_2
@c = $TXN[$i][@j].size
@k=1
while @k <= @c || $TXN[$i][@j][@k] != nil do
loop_3
@k +=2;
end
@j +=2; @k = 1;
end
$i +=1;
end
end

def loop_1
puts $TXN[$i]
puts "AT LOOP 1"
end

def loop_2
p $TXN[$i][@j]
p "value of i #{$i}, j is #{@j}"
puts "AT LOOP 2"
end

def loop_3
puts $TXN[$i][@j][@k]
p "value of i #{$i}, j is #{@j}, k is #{@k}"
puts "AT LOOP 3"
end

check
****************************************

regards,
Naresh

Attachments:
http://www.ruby-forum.com/attachment/3337/script_data.xml

 

[Brian Candler]

Following is my Ruby Code Wherein I am reading an XML file.
I am afraid why my loop is not getting incremented for value of i.

STDERR.puts "About to increment $i:"

$i +=1;

STDERR.puts "Value is now #{$i}"

I think you're going about debugging in a reasonable way: just keep
putting more debugging lines in until you find the problem. Don't be
afraid to put your debugging code straight inline. I tend to put it
lined up with the left-hand column, so it's easy to spot and rip out
later.

Incidentally, you have a strange mixture of global variables ($i) and
instance variables (@a). Normally you would just use local variables,
and pass in any parameters as required, like this:

def check(txn)
i = 0
a = tnx.size
while i <= a #|| txn != 0
.. etc
end
end

doc = Document.new File.new("script_data.xml")
txn = XPath.match(doc, "//TXN[@value]")
check(txn)

OR: you would make a class, and keep only those values you wish to
persist in instance variables. e.g.

class TXN
def initialize(txn)
@txn = txn
end

def check
i = 0
a = @txn.size
while i < a
... etc
end
end
end

doc = Document.new File.new("script_data.xml")
txn = TXN.new XPath.match(doc, "//TXN[@value]")
txn.check

This latter case is useful when you want to add more methods into your
TXN class, which operate on the same data, or you wish to bundle
together the txn with additional objects or data, and pass them around
as a single entity.

 

[List.rb]

Following is my Ruby Code Wherein I am reading an XML file.
I am afraid why my loop is not getting incremented for value of i.
Attached is the XML file for your referance.

********************************
require 'rexml/document'
require 'rio'
include REXML

$doc = Document.new File.new("script_data.xml")

$TXN = XPath.match($doc, "//TXN[@value]")

$i = 0

def check
@a = $TXN.size
while $i <= @a #|| $TXN[@i] != 0 do
loop_1
@b = $TXN[$i].size
@j=1
while @j <= @b || $TXN[$i][@j] != nil do
loop_2
@c = $TXN[$i][@j].size
@k=1
while @k <= @c || $TXN[$i][@j][@k] != nil do
loop_3
@k +=2;
end
@j +=2; @k = 1;
end
$i +=1;
end
end

def loop_1
puts $TXN[$i]
puts "AT LOOP 1"
end

def loop_2
p $TXN[$i][@j]
p "value of i #{$i}, j is #{@j}"
puts "AT LOOP 2"
end

def loop_3
puts $TXN[$i][@j][@k]
p "value of i #{$i}, j is #{@j}, k is #{@k}"
puts "AT LOOP 3"
end

check
****************************************

regards,
Naresh

Attachments:
http://www.ruby-forum.com/attachment/3337/script_data.xml

Doesn't File.new create a new file? Cant recall off hand..