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catching exceptions - file handling
Exceptions. example from a Well House Consultants training course
More on Exceptions. [link]
Source code: chq Module: R111
#!/usr/bin/env ruby
def byvalue (a,b,datasource) return datasource[b] - datasource[a] end # catching exceptions - file handling counter = {} total = 0 # --------- Read whole file begin stuff = (File.new ARGV[0]).readlines # - Action on FAILURE rescue STDERR.puts("Problem was #{$!} ...") STDERR.puts("should we shut down nicely?") stuff = [] # could exit instead #- Action on success else puts "Vunderbahl! we have opened our file" end # ---------- # Analysis of Data for line in stuff ip = (line.split)[0] # create a new element in the hash if necessary counter[ip] = 0 unless counter[ip] # and count the IP addresses counter[ip] += 1 total += 1 end #- Ruby sorting via a sort function #- How to sort a ruby hash by key tops = 0 for ipv in counter.keys.sort { |a,b| byvalue a,b,counter } puts "#{counter[ipv]} visits from #{ipv}" break if ((tops += 1) > 10) end puts "Total of #{total} records analysed" __END__ munchkin:rs grahamellis$ ./chq ac_20110907 Problem was No such file or directory - ac_20110907 ... should we shut down nicely? Total of 0 records analysed munchkin:rs grahamellis$ ./chq ac_20110908 Vunderbahl! we have opened our file 12751 visits from 83.170.93.77 10968 visits from 157.55.116.37 5483 visits from 217.160.182.81 5208 visits from 67.195.111.173 5175 visits from 66.249.72.203 3546 visits from 157.55.116.27 2885 visits from 66.249.72.76 1508 visits from 94.169.96.238 1386 visits from 67.195.37.188 1295 visits from 207.46.13.97 1105 visits from 66.249.72.111 Total of 127387 records analysed munchkin:rs grahamellis$ Learn about this subject
This module and example are covered on the following public courses:
* Learning to program in Ruby * Ruby Programming Also available on on site courses for larger groups Books covering this topic
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Other Examples
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