Ruby Language Quick Reference For Ruby On Rails Development development by Someshwar Mirge - January 12, 2021January 12, 20210 As you already know that learning Ruby language basics is vital for Ruby On Rails development . This Ruby language quick Reference For ruby on rails development will help you going. So in this Ruby language Quick Guide , we go from absolute basics to intermediate level of Ruby language . We will cover ruby language syntax and implementation of general programming terms like variables, control statements , loops , functions / methods , and various Object Oriented Programming concepts like classes , objects and packages / modules. We will also take a brief view at file handling with ruby . So let’s get started !! We will proceed section wise , following are the sections covered Ruby BasicsMethods in RubyObject Oriented Programing (OOP) In RubyFile Handling 1. Ruby Basics “Ruby is a dynamic , object oriented and general purpose programming language” Note : each and everything in Ruby is OBJECT. Ruby is Open Source . Hello world : Now , lets write our first program i.e. obviously ” hello, world!” puts “Hello , world!” print “Hello, World!” we can use either of the 2 methods . But the main difference between using puts and print is , puts use a “\n (new line character ) ” at the end of the output line and print don’t . commenting code : single comments : use ‘ # ‘ symbol to create a single line comment #this is sample single line comments multiline comment starts with ‘ =begin ‘ and ends with ‘ =end’ =begin sample multiline commnet =end Variables variables are ‘ names of storage locations ‘ lets understand with example : m=9 here m is a variable name and m is assigned value 9 . we will learn about assignment in later sections of this guide. NOTE: Variable name can contain either alpha numeric characters or underscore (_). But must not start with number or capital letter. Constants: A name of storage location just like variable , But variable values can be changed and constant remain , as its name suggest ‘constant /unchanged ‘ through out the execution of program . Note : constant names start with capital letters. example : rubyOnRails is a variable while RubyOnRails is a constant. Just use a capital letter at beginning and it become a constant. Data Types: any program / software / application is ultimately made to handle a data of some sort . Data Type is basically type of a data that a variable can contain. In ruby , any variable can be of any data type and ruby automatically determine datatype of a variable . example : tony= 3000 #int stark =1.2 #float ironman=” avenger ” #string Operators Mathematical Operations : Ruby supports all the arithmetic operations like addition (+) subtraction (-) multiplication (*) division (/) modulo division (%) exponent operator (**) a=5 b=6 c=a+b # addition c=b-a #subtraction c=a*b #multiplication c=a/b #division c=a%b #modulo devision c=a**b #this raises 5 to the power of 6 Note : To get float result after division operation , use any one float number . Note : all operators can be used with floating point numbers also Assignment : This one is not the assignment given in college ? . This is assignment operator mentions above in the variable section . We will check out assignment operator and some techniques of assignment . assignment operator is used to put value in the variable or constant . denoted by equal sign (=). Note : (=) is assignment and (==) is comparison don’t get confused here. Shorthand Assignment/self assignment This type of assignment is used to reduce code length . examples: a+=b # same as a=a+b likewise all the arithmetic operators can be used with self assignment operator Parallel Assignment: Lets have a look at one of the most convinient features in ruby. example : case 1 : normal assignment a=100 b=200 c=300 case 2 : parallel assignment a,b,c=100,200,300 a,b=b,a #number swapping as you can notice the difference , case 1 takes more efforts than case 2 , While case 2 makes workflow smoother ? Operator Precedence: It is importance given to operators. As shown below, operators are listed from higher to lower order of their precedence . ExponentiationMultiplicationDivisionModulus operatorAdditionSubtraction Note : order of execution can be changed using paranthesis () . Strings : Now , we have completed operators , lets learn about strings . String is nothing but anything enclosed between double or single quotation marks. [ ‘ ‘ or ” “] Note : always prefer double quotes for creating or manipulating strings , single quotes have many restrictions while operating . many escape sequences and characters can not be used with single quotes. Single quotes also doesn’t support string interpolation , which we will be discussing in next section. example: text = “Avengers end game is awesome movie “ String Interpolation : Here comes the awesomeness of strings . Using string interpolation property of ruby strings , we can embed any value inside a double quoted string using #{} . Note : while using #{} , please make sure there is no space in # and {. example: num1=10 num2=20 puts “The sum is #{num1+num2}.” Here , the part #{num1+num2} will be replaced by actual sum of num1 and num2 while executing. String concatenation : While working with actual projects , we often need to join two or more strings together . The same functionality is provided by concatenation .Here we can join 2 or more strings together. example: dialog1 = ” what can I do for you ?” dialog2=”Sir!” puts dialog1+dialog2 #result : “what can I do for you ? sir !” In this way you can add multiple strings together and join them. Note : just make sure you are not adding any number with strings . Although + sign is same in case of numbers and strings , both work differently according to context . String Repeatition: We can repeat strings without printing multiple times. example: text = “hey!” puts text*5 #outputs : “hey!hey!hey!hey!hey!” note : Never ever multiply a string by another string . It just throws error . But I know you are going to do it . so just check it !? and here we finish our string part . Input : For making any program / app/ software interactive , the must have thing is user input . So let’s see , how we can get user input in ruby language. To get input , ‘gets’ method is used. example: text=gets puts text #this outputs user entered input Now let us see , how we can modify functionality of gets according to our custom input requirements. chomp – by default gets method return string with a \n character at end so chomp is used to get input without the new line character.to_i –> integer number input.to_f –>floating point number input.to_s –>string type input.to_a –> array input.to_r –>fractional number input.to_h –> hash input (we will discuss hashesh in later part ).to_c –>complex number input .to_sym –> symbol input example: puts ” Enter Name:” name=gets.chomp puts “Welcome , #{name}” here we have used chomp to remove \n character from the end of input . In similar fashion , we can use .to_i to get integer number input and other types of inputs also. Booleans : This is special data type where , value of variable can only be either True (1)? or false (0) ? . example : isAlive=True isDead=Flase Note : Its general rule that boolean types of variable names should be like a verbal question , that should answer either true or false. In above example, variable like isAlive can be used to create a game app. Comparison Operators :(==, !=,<,>,<=,>=) These operators are used to compare two entities. It returns true if condtition satisfies and false is not. Another method to compare entities is to use .eql method . example: x=2 y=3 puts x==y #outputs false example 2: puts 3.eql?(3.0) #false (.eql method compare data types) we will continue with Ruby language quick Reference For ruby on rails development in next blog post, Stay tuned for more updates.