2.4 Scr0140: arithmetic operators

Table of contents

• Preface
  • Viewing tip
    • Images
• General background information
  • Operators
  • Operands
  • Expressions
  • Statements
  • A brief word about type
  • Unary, binary, and ternary operators
    • Some operators can be either unary or binary
    • The minus character as a unary operator
    • Binary operators use infix notation
  • General behavior of an operator
  • Operator categories
• Preview
• Discussion and sample code
  • Four variables
  • A button
  • Two scripts in the center panel
  • Variables with sliders
    • How to create a slider
  • Full-size view of the center panel
  • Initialize the variable values to zero
  • Define the behavior of the button
    • Constructing the script
    • Not exactly what we want to happen
  • The Operators panel
    • Four arithmetic operators
    • Use an asterisk for multiplication
    • Use a forward slash for division
    • More blocks of the correct shape
    • Random numbers
    • The modulus
    • Various numeric representations
    • Rounding a number
  • Drag and drop the plus and minus operators
  • A few more steps are required
  • Operation of the program
  • An online version of this program is available
• Run the program
• Student programming project
• Summary
• What's next?
• Resources
• Miscellaneous

Preface

This module is one in a collection of modules designed to help beginners of all ages (8 and up) learn how to create the code for computer programs. Information is provided not only for the beginners themselves butalso for their parents and teachers where appropriate.

The purpose of this module is to teach you about operators and operands in general and arithmetic operators in particular. You will also learn about expressions and statements, and you will learn how to write a Scratch program that illustrates the use of arithmetic operators in Scratch.

I will also provide the specifications for a student-programming project for you to complete in order to demonstrate your understanding of what you learnedfrom the first program.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the images while you are reading about them.

Images

• Image 1 . Reduced screen shot of Arithmetic01 in operation.
• Image 2 . Full-size view of the center panel.
• Image 3 . Preparing to use the arithmetic operators.
• Image 4 . Result of dropping addition and subtraction operators into variable blocks.
• Image 5 . Stage area of the finished program.
• Image 6 . Making the button say ouch.
• Image 7 . Output from student project program named Arithmetic02.

General background information

Operators

Operators are the action elements of a computer program. They perform actions such as adding two variables, dividing one variable by another variable,comparing one variable to another variable, etc.

Operands

According to the current jargon, operators operate on operands .

For example, in the following expression, the plus character is an operator while x and y are operands.