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Ruby introduction part1






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    Ruby introduction part1 Ruby introduction part1 Presentation Transcript

    • A Brief Introduction to Ruby : P1(Book Review of “Learn to Program”) Brady Cheng http://bradyisstudying.blogspot.tw/
    • AgendaInstallCommentData TypesVariables, Arrays, and IteratorsMethodsFlow Control
    • InstallFor Windows http://rubyinstaller.org/For Mac Build-inI strongly recommend you to use Mac or Linux to develop Ruby programs. But in this tutorial, I am gonna use Windows since I am stiff-necked guy 
    • CommentComment in Ruby is similar to Perl Ruby Perl # comment a line # comment a line =begin =pod Comment a block Comment a block =end =cut
    • Data Types Numbers puts 1+2 #3 Integer print puts 2*3 #6 puts 5-8 #-3 Float puts 9/2 #4 Letters puts 9.to_f/2 #4.5 String Cast to float -------------------------- puts ‘Enter a string’ #Enter a string More: puts gets.chomp #input from keyboard .to_i puts ha*3 #hahaha .to_s puts=<STDOUT>Repeat 3 times gets=<STDIN> chomp=delete last char
    • Variables, Arrays, and Iterators In C/C++, we write int a = 1; in Perl, we write $a = 1; in Ruby… a= 1 Yes, just write a a= 1 b = ‘2’ c = a.to_s + b #12 Cast a to string Add(+) = conj strings
    • Variables, Arrays, and Iterators Arrays [ele1, ele2, ele3] Some array methods .pop .push .join(‘join string’) .last .length
    • Variables, Arrays, and Iterators There is a special array method : each iterator An array with 3 elements color= [‘R, G, R] color.each do | c | | c | = variable in this puts “color=” + c do…end block end Output= color=R color=G color=B
    • MethodsIf objects(variables, arrays, …) are nouns inEnglish, then methods are verbs! int=noun We say “int, convert to string” to_s=verb int.to_s Sometimes we just say a verb without any noun, ie. GO! gets User defined methods
    • MethodsSome fancy string methods .reverse .upcase .downcase .swapcase .capitalize .center (width) .ljust width .rjust width
    • MethodsSome number methods ** #exponential % #modular .abs #absolute value rand(number) #generate a random number srand(seed) #generate a random seed
    • MethodsMore on user defined methods, similar to Python!def functionName (arg1, arg2) #do something return ret_valend Actually we don’t have to return because…. Case1: the function doesn’t have to return Case2: the last line is the default return value
    • Flow ControlConditional flow controlLooping flow controlif condition1 while condition #do something #do somethingelsif condition2 end #do somethingelse #do somethingend Don’t forget end
    • The EndThe first part is over, please wait for the second partAny comments would be appreciatedWelcome to my study page http://bradyisstudying.blogspot.tw/