# Add files to array matching pattern **URL:** \ **Category:** Ruby\ **Created:** [October 5, 2007, 1:08am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381 "2007-10-05T01:08:55Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 1:08am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/1 "2007-10-05T01:08:55Z")
Hi all, I wanted to simply add files to an array. The files must match a pattern. I’m just starting with ruby so I really have to find my way in it. I tried something like: dir = “/home/leon/images” test = Array.new test \<\< Dir.new(dir).entries.each { |x| if 1 == 1 } Then I wanted to add a sort of if to that last line with a block ( I think I have to use a block). I tried this in irb, but it doesn’t give an error. What am I doing wrong here? Thanks in advance! ---
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 1:23am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/2 "2007-10-05T01:23:11Z")
Tried this: dir = “/home/leon/”; test = Array.new; test = Dir.new(dir).entries.collect { |x| x == ‘filezilla’ ? x : next } But that didn’t work also. It gives back: [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil] ---
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 1:35am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/3 "2007-10-05T01:35:31Z")
This would work: i = 0; dir = “/home/leon/”; test = Array.new; test = Dir.new(dir).entries.map! { |x| x =~ /filezilla$/ ? x : next }; test.compact Is the .compact needed? Can’t I get rid of that? ---
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 1:50am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/4 "2007-10-05T01:50:16Z")
On Oct 4, 2007, at 7:35 PM, Leon B. wrote: > This would work: > > i = 0; dir = “/home/leon/”; test = Array.new; test = > Dir.new(dir).entries.map! { |x| x =~ /filezilla$/ ? x : next }; > test.compact > > Is the .compact needed? Can’t I get rid of that? test = Dir.entries(“/home/leon”).grep(/filezilla$/) -Rob Rob B. [http://agileconsultingllc.com](http://agileconsultingllc.com) removed\_email\_address@domain.invalid ---
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 2:03am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/5 "2007-10-05T02:03:53Z")
Leon B. wrote: > This would work: > > i = 0; dir = “/home/leon/”; test = Array.new; test = > Dir.new(dir).entries.map! { |x| x =~ /filezilla$/ ? x : next }; > test.compact > > Is the .compact needed? Can’t I get rid of that? You can do something like this: d = “./” matching\_files = Dir.open(d) do |dir| dir.find\_all { |filename| filename == “r8test.rb”} end p matching\_files collect puts the return values from the block into an array. With find\_all, if the block returns true, then the current filename is added to the array. ---
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 5:25am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/6 "2007-10-05T05:25:16Z")
Leon B. wrote: > Tried this: > > dir = “/home/leon/”; test = Array.new; test = > Dir.new(dir).entries.collect { |x| x == ‘filezilla’ ? x : next } > > But that didn’t work also. It gives back: > > [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, > nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, > nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, > nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, > nil, nil, nil, nil, nil, nil, nil, nil, nil] The reason you get that output is: 1. collect adds the value returned by the block to a results array. 2. There is no file named “filezilla” in the directory /home/leon 3. That means the value of the block is always whatever is produced by the statement: next. If you try this: [1, 2, 3].each {|x| puts next} you’ll get the error r9test.rb:1: void value expression I think that means that the next statement is one of the few statements in ruby that doesn’t produce a value. So what is the value of the block when the next statement gets executed as the last statement? If you try this: results = [1, 2, 3].collect {|x| next} p results the output is: [nil, nil, nil] Look familiar? Apparently, a block returns nil by default if the statements in the block do not produce any values. ---
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 9:21am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/7 "2007-10-05T09:21:45Z")
2007/10/5, Leon B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > This would work: > > i = 0; dir = “/home/leon/”; test = Array.new; test = > Dir.new(dir).entries.map! { |x| x =~ /filezilla$/ ? x : next }; > test.compact > > Is the .compact needed? Can’t I get rid of that? You need it with your code because the map! will map some values to nil. You probably rather want #select. files = Dir.new(dir).entries.select { |x| /filezilla$/ =~ x } But you can have that much easier with files = Dir[“/home/leon/\*filezilla”] Kind regards robert ---
**Author:** ![leonb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/22d042/32.png) [@leonb](https://www.ruby-forum.com/u/leonb)\ **Post date:** [October 5, 2007, 5:41am UTC](https://www.ruby-forum.com/t/add-files-to-array-matching-pattern/116381/8 "2007-10-05T05:41:04Z")
Leon B. wrote: > This would work: > > i = 0; dir = “/home/leon/”; test = Array.new; test = > Dir.new(dir).entries.map! { |x| x =~ /filezilla$/ ? x : next }; > test.compact > > Is the .compact needed? Can’t I get rid of that? Also, next is used skip the rest of the code in a block. For instance: (1…4).each do |x| next if x==2 puts x end –output:– 1 3 4 On the other hand, using next as the last statement in a block does nothing: (1…4).each do |x| puts x next end –output:— 1 2 3 4 …except screw up the return value of the block: results = (1…4).collect do |x| x if x != 2 next end p results –output:— [nil, nil, nil, nil] For methods like collect that use the block’s return value, the next statement ruins the results array.