Computer Programming/Variables

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Flowchart displaying variables

This lesson introduces variables, constants, data types, expressions, statements, and order of operations.

Objectives and Skills[edit]

Objectives and skills for this lesson include:

  • Understand variables and constants.
  • Use integer, floating-point, and string data types appropriately.
  • Use expressions and statements to assign values to variables.
  • Understand the order of operations for arithmetic and logical operators.


  1. Wikipedia: Variable (computer science)
  2. Wikipedia: Constant (computer programming)
  3. Wikipedia: Data type
  4. Wikipedia: Expression (computer science)
  5. Wikipedia: Statement (computer science)
  6. Wikipedia: Assignment (computer science)
  7. Wikipedia: Order of operations
  8. Wikipedia: Input/output
  9. Wikipedia: Self-documenting code


  1. YouTube: Elements of High-Quality Programs
  2. YouTube: Programming/Scripting Concepts Explained (Variables, Arrays, Strings, & Length)
  3. YouTube: Programming For Beginners - Variables
  4. YouTube: Programming For Beginners - Data Types
  5. YouTube: Introduction to Programs Data Types and Variables
  6. YouTube: Introduction to Programming - Basics
  7. YouTube: Declaring and using variables and constants
  8. YouTube: Performing arithmetic operations
  9. YouTube: Introduction to order of operations
  10. YouTube: Python3 Input & Output



Complete the following activities using a flowchart tool, pseudocode, or your selected programming language.

  1. Review MathsIsFun: Order of Operations. Create a program that demonstrates the order of operations. Include parentheses, exponents, multiplication, division, addition, and subtraction in your program.
  2. Review Wikipedia: Data type. Create a program that demonstrates integer, floating point, and character or string data, and demonstrate converting between data types. For example, user input is always a string, but adding string values of "1" + "1" is typically "11", whereas, adding numeric values of 1 + 1 is 2.
  3. Create a program to prompt the user for hours and rate per hour and then compute gross pay (hours * rate).[1]
  4. Create a program that asks the user how old they are in years, and then calculate and display their approximate age in months, days, hours, and seconds.
  5. Review MathsIsFun: US Standard Lengths. Create a program that asks the user for a distance in miles, and then calculate and display the distance in yards, feet, and inches, or ask the user for a distance in miles, and then calculate and display the distance in kilometers, meters, and centimeters.
  6. Review MathsIsFun: Area of Plane Shapes. Create a program that asks the user for the dimensions of different shapes and then calculate and display the area of the shapes.
  7. Review Wikipedia: Zeller's congruence. Create a program that asks the user for their birthday (year, month, and day) and then calculate and display the day of the week on which they were born.

Lesson Summary[edit]

Key Terms[edit]

Sets the value saved in the storage location denoted by a given variable name.[2]
A data type having two values, typically denoted true and false.[3]
A value that cannot be altered by the program during normal execution.[4]
data type
A classification of data which tells the compiler or interpreter how the programmer intends to use the data.[5]
A language construct that specifies the properties of a given identifier.[6]
A combination of one or more explicit values, constants, variables, operators, and functions that a programming language interprets and computes to produce another value.[7]
floating point
The formulaic representation that approximates a real number to a fixed amount of significant digits.[8]
A number that can be written without a fractional component.[9]
The remainder after division of one number by another.[10]
A programming language construct that performs a calculation from zero or more input values to an output value.[11]
order of operations
A collection of rules that reflect conventions about which procedures to perform first in order to evaluate a given mathematical expression.[12]
real number
a value that represents a quantity along a line, including integers, fractions, and irrational numbers.[13]
The smallest standalone element of an imperative programming language that expresses some action to be carried out.[14]
A sequence of characters, either as a literal constant or as some kind of variable.[15]
A storage location paired with an associated symbolic name (an identifier), which contains some known or unknown quantity of information referred to as a value.[16]


See Also[edit]