1 / 19

Variables

Variables. What will we learn today?. What Are Variables Variables in Real-Life Variables in Programs Types of Variables Creating a Timer Example. Variables. A Variable is a storage location (place in computer’s memory) which contains information

swest
Download Presentation

Variables

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Variables

  2. What will we learn today? • What Are Variables • Variables in Real-Life • Variables in Programs • Types of Variables • Creating a Timer Example

  3. Variables • A Variable is a storage location (place in computer’s memory) which contains information • Variables are analogous to "Buckets" or "Envelopes" where information can be maintained and referenced • Each variable has a name (an identifier), a type and a value (piece of information) • E.g. (a=5, b=“hello”) • Variables allow us to keep track of changes as our program runs

  4. Variables in Real Life • We use variables to track the balance of money in a bank account • We use variables to track the amount of gasoline in the tank of the car

  5. Variables in Programs • We often need to keep track of changes in position, color, and other properties of objects in our programs • In a game, we may want to keep track of number of steps or times or numbers of goals..etc • For example, we want to know the number of times a player has put the basketball through the hoop or how much time is left on the clock

  6. Types of Variables • Numeric • They can store a whole number value, e.g. 7 or 1024 • Boolean • They can represent one of two states, true or false • Character/String • They can represent a single character, e.g. 'A' or '$‘ or a group of characters, e.g. “Ali” or “20 minutes left” • Object • They can represent a whole object, e.g. cat or fort

  7. A Timer for a Game Example • A timer is used in most of the games to keep track of how much time the player has left to play • We will construct a timer that counts down in seconds • Our task is to set the timer to an initial number of seconds (e.g. 10s) and then count down the seconds remaining in a game • The number of seconds remaining will be displayed and will be updated with each passing second • We will create a chicken that rotates around itself as the timer count down

  8. A Timer for a Game Example • Add a new object: a 3D text • Type 0.0 which is the value that appears when the time’s over

  9. A Timer for a Game Example • Rename the object to timer

  10. A Timer for a Game Example • Add a new variable in the timer object • Select the timer object • Select the properties tab • Click on the ‘create new variable’ button • Name it ‘timeLeft’ and set it to type ‘number’

  11. A Timer for a Game Example • Drag the ‘timeLeft’ to the ‘world.timer’ method • Create a new parameter and call it ‘amount of time’

  12. A Timer for a Game Example • Set the values as shown • Create a new method and call it ‘countDown’

  13. A Timer for a Game Example • Inside the method, add a while loop with expression ‘a<b’ and set ‘a’ and ‘b’ as follows • Drag the text inside the while loop

  14. A Timer for a Game Example • Set the value of the text as follows, drag ‘what’ from the functions box • Drag time left from properties insert it into the what box

  15. A Timer for a Game Example • Move the timer up and down • Make a function that returns the time left

  16. A Timer for a Game Example • The ‘countDown’ method • Create a method ‘playGame’ and set it as follows

  17. A Timer for a Game Example • The main method ‘world.myFirst’ method

  18. A Timer for a Game Example • Here is our Chicken

  19. Let’s Work with Alice • Counting Fishes A Scuba diver (people) wants to count the fishes (ocean) that eat from the Seaweed (ocean). Make a method where each fish goes to the seaweed, eats, waits, and comes back. As each fish does so, a counter on the top-right corner of the screen (3D-Text) increases by one. After all fish have eaten, the scuba diver says the final count of fishes. You will need to create a number variable ‘NumberOfFish’ for that.

More Related