COMP101: Final Review. With your boy(s), Mason and San

Transcription

1 COMP101: Final Review With your boy(s), Mason and San

2 COMP101 Happenings The COMP 101 final exam is still scheduled for tomorrow (December 12) at 12 pm in Genome Sciences Bldg. Seating assignments will go out later tonight. If you haven t gone over the Concepts Inventory Kris published yet, give it a read through! (Located under Practice Problems on the 101 website). This review session is pulling material directly from here. Relax! You got this!

3 Types Primitive Types: - number - string - boolean Non-Primitive Types: - arrays - classes

4 Three Ways of Instantiating a Primitive Variable The keyword let must come before any variable declaration. The name you give a variable is inconsequential (but important when reading code!) The assigned value for the variable always goes to the right of the = sign. Assigning a type in the variable declaration is optional (type inference).

5 Reassinging Number Variables let a = num; let b = num - a += b (a is assigned to itself plus b) - a -= b (a is assigned to itself minus b) - a *= b (a is assigned to itself multiplied by b) - a /= b (a is assigned to itself divided by b) -

6 Practice w/ Primitives STRING NUMBER STRING BOOLEAN 64 STRING NUMBER STRING

7 What are the final values of a, b, and c? Answer: 100, 0, 5

8 Boolean Operators AND: (&&) OR: ( ) NOT: (!) - T && T = T - F && T = F - F && F = F - T T = T - T F = T - F F = F -!T = F -!F = T -

9 Number Operators ARITHMETIC: = = 1-9 * 8 = 72-9 / 8 = % 8 = 1 RELATIONAL: - 9 === 9 = T - 9!== 9 = F - 9 > 9 = F - 9 >= 9 = T - 9 < 9 = F - 9 <= 9 = T

10 String Concatenation: Adding but for strings Notice that the type of the entire output is a string!

11 Swapping Variables: Practice \\ A A K K 3 2

12 Looping: Two Kinds While-loop For-loop

13 Which to use? In the last case, both loops accomplished the same task. For loops are often preferred because they tend to be more concise. While loops may be the better choice in situations where the looping condition isn t a conditional operator.

14 Loops that don t do what you expect: Debug these code snippets and try and find errors i++

15 Arrays: Creating Arrays Directly Memory: A B C D E F G

16 Arrays: Assigning Values The syntax for assigning values to array indices is as follows: let arr = []; arr[0] = 1; name index value

17 Three Ways of Instantiating an Array You may also use type inference when instantiating arrays. You can directly populate an array using the method shown on the right, but let s say you re asked to create an array with numbers counting from Which of the three ways would you use?

18 What s wrong here? Arrays act like objects in that you cannot access an array s properties (length, indices), until it has been instantiated.

19 Practice Problem: Accessing and Assigning to Indices What is the pattern in how this program changes the values in the array? What causes this? What is the final value of the array arr? [0, 2, 0, 4, 0, 6, 0]

20 Mid Review Break: Please use Course.Care to check in for today s review session! Link to be provided. 4AA37

21 Instantiating an Object: the new keyword book: pages: 455 title: The Goblet of Fire

22 Type Inference with Objects: book: pages: 455 title: The Goblet of Fire Note: we ve still included the new keyword!

23 Changing an Object s Default Properties book: pages: title: Goblet Breaking of Dawn Fire

24 Object s Have Types! The type of an object is the class that it was modeled upon! In the first case, we made an object of type Book called hp, and that book object is comprised of two properties: a number property called pages and string property called title. Where do we get this information? The class definition!

25 Object s Have Types! Class Def. The object s type

26 Jump to object definition 2 Set default property 3 Set default property 4 Set default property 5 Initialize object 1 Access and edit property Access and edit property 6 7 Access and edit property 8 In what order does the code run? Student name: age: 0 21 Mason hasgrapefruit: false true

27 The Anatomy of a Function

28 Jump to main Call add Print seven Stop executing 7 Jump to add Execute add 4 5 Call main 1 In what order does this code run?

29 7 7 Arguments, Parameters, and Returned Values What are the arguments? 2. What are the parameters? 3. What is the return value? 4. What is the value of seven?

30 Returning from within a Function Both of these functions should maximize the input array and return 10, but one of them does it wrong. Where does it mess up?

31 Scope The variable n3 may be accessed anywhere in this code because it s a global variable. The variables n3 and n4 may only be accessed within the function named c, and vice versa for the other variables.

32 Calling Functions: Practice What is printed when the following code runs? Answer:

33 Linear Search - Linear search iterates through an array until the item in question is found, or until the end of the array is reached. - If you were to consider an array billions of items long, you might see how linear search breaks down!