Comptuer Studies Ruby Notes

These be notes I took while I was learning Ruby. Comptuer studies ruby notes Instance of a twelvemonth is a sub-category of that class. E. g. greyhound dog. all object has a class. Objects are instances of classes. Methods define what an object pile do and properties describe it. Constants start with a capital letter, sometimes they are all caps e. g. lodge in = 0. 012 setting constant INTEREST to 1. 2% DOZEN = 12 setting constant DOZEN to 12 Constants and variables store information in the memory for the date of the use of the program.Like RAM? Constants gouget be changed scarce variables can be reassigned based on certain properties and data. Different types of classes affiliateExample of Object Float6. 5 or 3. 9 Fixnum2 or 3 StringThisisastring or random enactment34 ArrayMonday Tuesday Wednesday Thursday Friday Or January February March April HashToronto Dion Phaneuf Pittsburgh Sidney Crosby Washington Alex Ovechkin Or Haseeb November 18 Humza August 6 Hana August 11 Ran ge11.. 20 Or Hi.. Ho Float = decimal number Fixnum/Integer = whole number String = letters and numbersArray = an ordered list, a couple of objects put together in one list that can likewise be accessed independently Create a new array or reset an old one by exploitation this array = Array. new You can also show individual variables by doing arraynumber e. g. subjects3 you can also add objects to the array by subjects 4 = Social Science Hash = Similar to array but not in order, each object does not have a number. Its based on key and value pairs. Like if you put pentad names and assigned each a birthday. They would go based on those pairs. It assigns the first name to the second. E. g friends = Hash. ew friendsAndrea = July 22 friendsMohammed = April 9 Range = A sequence of set e. g. nums = 11.. 20 Setting variable Fav_food = pizza setting variable fav_food to pizza The quote marks around pizza identify that fav_food is a string value. Identifiers are the constant/variables name s In order to change a variables value (not class) from one to another use the following To string x. to_s To bluster x. to_f To integer/fixnum x. to_i Keep in mind, this only changes the variables value based on class properties, not its actual class Scope is where the variable can be accessed r seen within a program. Some are only used for a small task while others may be used for large tasks and appear several times within the program. Constants scope depends on how often it is state. If a constant is only declared within a class or module its scope is within that scope or module. However if it is declared outside of that class or module its scope is wider or global. There four different variable scopes. Local variables are confined to the part of the program in which they are declared. If the variable is only declared within a method it is restricted to when that method is used or executed.It cant be used anywhere else in the program. (e. g. fav_food) spherical variables can be declared anywhere in the program and are accessible from anywhere in the program. They are identified by a preceding $ e. g. $fav_food. Global variables, however have to be used with extreme caution due to the fact that their values can be changed anytime in the program, sometimes by inadvertent or careless coding, these accidents can cause huge problems and are not easily fixable. Class variables are confined to a specific class but once all instances of the class are created the value of the variable is shared amongst all instances.If the value is changed in one of the instances, it is changed in all of the instances. (e. g. fav_food) Instance variables are restricted to only certain instances of a class. If the value changes in one of the instances it stays the same in the others. (e. g. fav_food) Commands to determine classes Either puts variable. class or puts variable. kind_of? Class The first will tell you what class the variable is while the other will say true or fals e based on what class is inputted at the end of the line. Changing classes The easiest way is to just assign a new value to it.Another way is to use the to_s, to_i etc. commands while also using the = assignment operator in order to change the objects class permanently e. g. num = num. to_s you can do it without the = and the num variable before the equals sign in order to change it temporarily All math operations are the same except for two. Modulo (%) Divides and gives the remainder and exponent is (**). E. g X = 6%4 X = 20 ** 2 There are also comparison operators such as puts a == b false as a and b are not equal puts a = b true as a and b are not equal puts a b returns true as b is larger puts a