Storing data Getting data out Data types Ruby as a foundation Program Variables Click icon to hear comments (the download may take a minute)

Assigning a value to a variable The variable name on the left side of the equal sign gets a value assigned to it. – A value can be assigned to give a name to a number LegalAge = 21 – A variable name may be easier to remember than a number and thus, help to make programming easier – imagine having to remember and type when you want to reference the number of milliliters per pint mlperpint = Click icon to hear comments

Getting data out of variable To use the value stored in a variable, use the name is if it were the value itself – The value might be printed for display purposes PRINT “The legal age is #{LegalAge}” – The value might be used for a calculation legalBirthDate = DateToday - LegalAge – The value be used for a decision IF age < LegalAge Then PRINT “too young” Click icon to hear comments

Numbers or Letters? Because of the way computers store and manipulate data, different types of variables are used. Use a numeric data type for math operations Data type can affect – the amount of memory used – the way decimals are handled – The number of digits that can be stored – how rounding or fractional values are handled Click icon to hear comments

String Data Type The letters, numbers, and symbols on the keyboard are called alphanumeric string is often used as a shorter way of referring to alphanumerics. Quotations marks surrounding text indicates string data. FirstName = “Petulla” In VisualBasic, the words as string are used when the variable is defined. Click icon to hear comments

Data types in Ruby and other languages For simplicity, in Ruby a variable is considered a string type by default if input is from a keyboard – String values need to be converted to numeric before performing math. – Floating point data type can also be specified by assigning a value with a decimal point, otherwise integer is assumed mlPerPint! = – In VisualBasic the words as single are used when the variable is first defined. Click icon to hear comments

Other Data Types in Ruby and symbol used Values too large for Fixnum are automatically converted to Bignum—both are subclasses of integer Integer – Whole numbers up to 1 less than the native machine word are stored as Fixnum Other number bases – Hexadecimal - precede value with 0x – Binary – precede value with 0b – Octal – precede value with 0 Click icon to hear comments

Other Data Types in VisualBasic and symbol used In addition to the data types supported by Ruby, VisualBasic has several, such as: – Boolean - True or False – Char – single Unicode character followed by lowercase c “A”c – Decimal – up to 29 digits followed by D 59.99D – Date – days since year 1 enclosed in # #1/1/2001 1:00 PM# – Double ± followed by R – Object– can store and convert to other types Click icon to hear comments