Introduction

Ruby is a pure object-oriented programming language. It was created in 1993 by Yukihiro Matsumoto of Japan.

Ruby is "A Programmer's Best Friend". Ruby has features that are similar to those of Smalltalk, Perl, and Python. Perl, Python, and Smalltalk are scripting languages.

Smalltalk is a true object-oriented language. Ruby, like Smalltalk, is a perfect object-oriented language. Using Ruby syntax is much easier than using Smalltalk syntax.

Features:

Example:

puts 'hello ruby'

Above code prints hello ruby to the screen

Remember This

Extension:

Ruby file Extension:.rb

Whitespace

Whitespace characters such as spaces and tabs are generally ignored in Ruby code, except when they appear in strings.

a + b is interpreted as a+b ( Here a is a local variable) a +b is interpreted as a(+b) ( Here a is a method call)

Line Endings

Ruby interprets semicolons and newline characters as the ending of a statement.

However, if Ruby encounters operators, such as +, −, or backslash at the end of a line, they indicate the continuation of a statement.

Identifiers

Identifiers are names of variables, constants, and methods.

Ruby identifiers are case sensitive.

It means Ram and RAM are two different identifiers in Ruby.

Ruby identifier names may consist of alphanumeric characters and the underscore character ( _ ).

Comment:

Single Line Comment:

# I am a comment. Just ignore me.

Multi Line Comment:

=begin This is a comment. This is a comment, too. =end

Variables

Variables are the memory locations, which hold any data to be used by any program.

We are covering local variables only! See the reference at the end to know more about other types!

Local Varibales

  • Local variables begin with a lowercase letter or _.
  • The scope of a local variable ranges from class, module, def, or do to the corresponding end or from a block's opening brace to its close brace {}.
  • When an uninitialized local variable is referenced, it is interpreted as a call to a method that has no arguments.
  • Assignment to uninitialized local variables also serves as variable declaration.
  • The variables start to exist until the end of the current scope is reached.
  • he lifetime of local variables is determined when Ruby parses the program.

    • math = 100 science = "awesome"

    Literals

    Integers

    Ruby supports integer numbers.

    An integer number can range from -230 to 230-1 or -262 to 262-1.

    123 -500

    Floats

    Ruby supports floating numbers.

    hey are also numbers but with decimals.

    124.4

    Strings

    Ruby strings are simply sequences of 8-bit bytes and they are objects of class String.

    Double-quoted strings allow substitution and backslash notation but single-quoted strings don't allow substitution and allow backslash notation only for \\ and \'

    puts 'escape using "\\"'; puts 'That\'s right';

    Result:

    escape using "\" That's right

    Statements

    if...else

    x=1 if x > 2 puts "x is greater than 2" elsif x <= 2 and x != 0 puts "x is 1" else puts "I can't guess the number" end

    Result:

    x is 1

    unless

    Executes code if conditional is false. If the conditional is true, code specified in the else clause is executed.

    x = 1 unless x >=2 puts "x is less than 2" else puts "x is greater than 2" end

    Result:

    x is less than 2

    Loops

    while

    Executes code while conditional is true. A while loop's conditional is separated from code by the reserved word do, a newline, backslash \, or a semicolon ;.

    i = 0 num = 3
    while i < num do puts i end

    Result:

    0 1 2

    until

    Executes code while conditional is false. An until statement's conditional is separated from code by the reserved word do, a newline, or a semicolon.

    i = 0 num = 3
    until i > num do puts i end

    Result:

    0 1 2 3

    for

    Executes code once for each element in expression.

    for i in 0..2 puts i

    Result:

    0 1 2

    This is a very basic documentation, To learn elaborately click here!