first commit

10F/NilClass.rb

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+p
+puts
+print

10F/String.rb

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+String - collection of characters
+
+str = String.new
+=> ""
+
+str = ""
+
+str = "Hello world"

10F/array.rb

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+Array - collection of similar data types
+
+r = Array.new
+=> []
+
+r = []
+
+r << 1
+r << 2

10F/conditions.rb

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+if condition
+
+if condition
+  logic # if the condition is true
+end
+
+OR
+
+if condition
+  logic # if the condition is true
+else
+  logic # if the condition is false
+end
+
+
+if condition1
+  logic # if the condition1 is true
+elsif condition2
+  logic # if the condition1 is false and condition2 is true
+elsif condition3
+  logic # if the condition1 and 2 is false and condition3 is true
+else
+  logic # if all above conditions are false
+end
+
+
+unless condition
+  logic # if the condition is false
+else
+  logic # if the condition is true
+end
+
+
+case varaible
+when condition1
+  logic
+when condition2
+  logic
+else
+    no logic
+  end
+
+
+
+while condition
+  logic # if the condition is true
+end
+
+a = 10
+while a < 20
+  a += 1
+  puts "Hello"
+end
+
+
+until condition
+  logic #if the condition is false
+end

10F/fib.rb

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+def fib(n)
+  a, b = 0, 1
+  puts a
+  (1..9).each do | i |
+   puts b
+   a,b = b, a + b
+  end
+end
+
+fib(8)

10F/file_system.rb

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+File - is class
+
+method
+  read
+  write
+  open
+
+mode
+    r
+    w
+    wr
+    a+
+    wb
+    rb
+
+Q. take user name and email ans store into a file.
+
+

10F/hash.rb

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+Hash - store the value in key and value pair
+
+h = Hash.new
+=> { }
+
+or
+
+h = {}
+
+
+HOw to put values inside the hash
+
+h[:key]  = value
+
+How to get a value
+
+h[:key_name]

10F/loops.rb

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+Iterators
+
+each
+
+map
+collect
+
+
+SYNtax :
+
+collection.map/each/collect do | object|
+  logic
+end
+
+
+[1,2,3,4].map do | i |
+  i * 2
+end
+
+
+
+
+loop  - Explained
+
+for object in collection
+  logic
+end
+
+for i in [1,2,3,4]
+  puts i* 3
+end

10F/palidrome.rb

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+def palindrome?(str)
+  if str == str.reverse
+    true
+  else
+    false
+  end
+end
+
+puts palindrome?("mom")
+puts palindrome?("papa")

10F/prg1.rb

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+class A
+  def user
+    puts "Enter your name"
+    name = STDIN.gets.chomp
+    puts "Enter your address"
+    address = STDIN.gets.chomp
+    file = File.open('user_input', "a+")
+    file.puts name
+    file.puts address
+    file.close
+  end
+end
+
+r = A.new
+r.user

10F/prg2.rb

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+r = File.read('user_input')
+puts r.split("\n")

10F/range.rb

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+Range -
+(source..destination) # include the destination
+(source...destination) # exclude the destination
+
+(1..10)  => 1..10
+(1...10) => 1..9

10F/user_input

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+UN
+USA
+Bangalore
+ABC

10F/user_input.rb

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+
+file = File.open("user_input2", "a+")
+
+loop do
+ puts "Enter your name"
+ name = STDIN.gets.chomp
+ puts "Enter your address"
+ address = STDIN.gets.chomp
+ file.puts "#{name} #{address}"
+ puts "To continue please enter yes otherwise type anything to terminate"
+ response = STDIN.gets.chomp
+ if not response.match(/yes/i)
+   file.close
+   break
+ end
+end

10F/user_input2

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+hello bye
+world UN

11F/error_handling.rb

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+# begin
+#   code
+# rescue
+#   code
+# end
+
+# [1,2,3,0,4,5,6].each do | i |
+#   begin
+#     puts 100/i
+#   rescue Exception => e
+#     puts e.message
+#     i = 2
+#     retry
+#   ensure
+#     puts "I am present"
+#   end
+# end
+
+begin
+  puts "Enter your name, excluding admin and super"
+  name = STDIN.gets.chomp
+  raise "super and admin can't be taken as name" if name.match(/admin|super/)
+rescue Exception => e
+  puts e.message
+  retry
+end
+
+
+
+begin
+  code
+rescue NoMethodError
+  code
+end
+
+
+
+
+
+puts x = 100/0 rescue nil
+puts x = 100/2 rescue nil

12F/file1.rb

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+def find(str)
+  if str.match(/^(\d{2,3}.\d{2,3}.\d{1,3}.\d{1,3})\s(Safari|Chrome)\sUSA$/i)
+    puts "#{$1} and #{$2}"
+  end
+end
+
+
+File.read('log.txt').split("\n").each do | each_line |
+ find(each_line)
+end

12F/file2.rb

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+def email(str)
+  if str =~ /^[^!-)|_]\D.*@(gmail|yahoo).(in|com)/
+    puts "valid email - #{str}"
+  end
+end
+
+email("[email protected]")
+email("[email protected]")
+email("[email protected]")

12F/log.txt

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+192.168.1.1 Safari USA
+17.10.18.20 Chrome China
+1.3.4.1	Mozila USA	
+17.10.18.22 Chrome USA
+17.10.18.23 Mozila USA 

12F/regex.rb

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+Regex is a pattern matching or finding logic for a given string
+
+
+r =~ /patter/
+
+or
+
+r.mathc(/pattern/)

13F/.byebug_history

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+exit
+x1.count
+str_array.count("")
+str_array
+c
+x2
+str_array.count("")
+str_array
+c
+x2
+str_array
+x1.count
+str_array.count("")
+c
+x2
+str_array
+str_array.count("")
+c
+m
+c
+str_array.count("")
+x2
+str_array
+c
+x2
+str_array
+x1.count
+str_array.count("")
+c
+x1.count
+str_array.count("")

13F/a.rb

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+class A 
+  def p1
+    "An instance method"
+  end
+end

13F/b.rb

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+require_relative 'a'
+
+
+class B < A
+end
+
+b = B.new
+puts b.p1

13F/block.rb

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+def p1(t)
+  t = 20 + t
+  yield(t) if block_given?
+  puts "From method p1"
+  yield(t + 50) if block_given?
+end
+
+p1(10) do | i |
+  puts "I am a block n value is #{i}"
+end
+
+#OR
+
+p1(10) { | i |
+  puts "I am a block n value is #{i}"
+}

13F/grep.rb

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+irb(main):001:0> ["12", "Hello", "bye"].grep(/bye/)
+=> ["bye"]
+irb(main):002:0> ["12", "Hello", "bye"].map {| i | puts i if i.match(/bye/i)}
+bye
+=> [nil, nil, nil]
+irb(main):003:0> ["12", "Hello", "bye"].select {| i | puts i if i.match(/bye/i)}
+bye
+=> []