Debugging in Roblox Studio - AP CSP Roblox — Transcript

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1. 0:00hi in this lesson we'll talk about best
2. 0:03practices for finding and fixing bugs in
3. 0:05your programs
4. 0:07debugging is a process we use to fix
5. 0:09bugs or problems that find their way
6. 0:12into our programs as we develop them
7. 0:15debugging can be similar to reading an
8. 0:18iSpy book you're looking for something
9. 0:20small something that isn't quite right
10. 0:22in a big program it takes some patience
11. 0:25and focus
12. 0:28so what do we learn about debugging you
13. 0:31might think that you can simply avoid
14. 0:33bugs by writing good code
15. 0:35there are things that you can do to try
16. 0:37to avoid errors like keeping your code
17. 0:39neat and organized but the truth is
18. 0:41everyone even experienced programmers
19. 0:44write bugs
20. 0:45because of this debugging is really the
21. 0:48most important skill that programmers
22. 0:50learn
23. 0:51there are different types of errors that
24. 0:53can occur in a program
25. 0:55syntax are the rules for how to write
26. 0:57code the syntax can differ for different
27. 1:00programming languages
28. 1:02if there is an error in the syntax the
29. 1:05program won't run properly or may not
30. 1:07run at all
31. 1:08a logic error is an error in the code
32. 1:10that doesn't keep the program from
33. 1:12running but it doesn't do what it's
34. 1:14supposed to do these are usually harder
35. 1:16to find and fix when compared to syntax
36. 1:18errors
37. 1:21when a runtime error occurs the program
38. 1:23starts running but then crashes later on
39. 1:26something that might cause a crash like
40. 1:28this could be a player input that runs a
41. 1:31function that then has an error
42. 1:34let's take a closer look at syntax
43. 1:36errors a syntax error is a mistake in
44. 1:39how the code is written computers only
45. 1:41understand commands if they're written
46. 1:43with specific rules if the syntax is not
47. 1:45exactly correct the code won't run there
48. 1:48are a lot of ways this could happen the
49. 1:50command on the screen is correct as
50. 1:52written but let's look at a few common
51. 1:54mistakes that could occur
52. 1:56here we use the lowercase M instead of a
53. 1:59capital M this gives us an error and the
54. 2:02script won't run properly
55. 2:05here we forgot the quotes around the
56. 2:07string Rock and we get another error
57. 2:11logic errors can be harder to spot the
58. 2:14code on the screen will run with no
59. 2:16errors but it may not run as intended by
60. 2:19the programmer in this program there are
61. 2:21two players and we want to print their
62. 2:23combined scores but when we run this
63. 2:26program the total score is printed as
64. 2:2918. it should be 9 plus 5 which is 14.
65. 2:33so what's going on where's the error
66. 2:36foreign
67. 2:37well it looks like we have player one
68. 2:40score being added to itself instead of
69. 2:43adding Player 1 and player 2 scores now
70. 2:46let's fix this
71. 2:48we change player one score to player 2
72. 2:51score now when we run the program it
73. 2:54prints 14 and runs as intended problem
74. 2:56fixed
75. 2:58there are several strategies that make
76. 3:00it easier to debug a program keeping
77. 3:02your code neat and organized can help a
78. 3:05lot in finding a problem
79. 3:07this includes adding informative
80. 3:09comments using descriptive variable
81. 3:11names and by using functions to avoid
82. 3:14repetitive code
83. 3:16most programs you develop will perform
84. 3:18multiple actions you can use comments to
85. 3:21section out your code and only run
86. 3:23through it bit by bit this will help to
87. 3:26isolate the problem which will make it
88. 3:28much easier to fix
89. 3:30to do this you can highlight the section
90. 3:33of code that you want to comment out and
91. 3:35hit shift and forward slash
92. 3:38Roblox Studio includes a few debugging
93. 3:41tools as well the output window is very
94. 3:44helpful in debugging programs this
95. 3:46window displays errors captured from
96. 3:48running Scripts
97. 3:50you can click right on the message to be
98. 3:52taken to the mistake
99. 3:54in this image it looks like we mistyped
100. 3:56the word ladder well that's an easy fix
101. 4:01you can also use the output window along
102. 4:04with print statements to make sure your
103. 4:06scripts and functions are set up
104. 4:07correctly here a debug print statement
105. 4:10is printed to the output when the
106. 4:12function runs this way you know that
107. 4:14it's running correctly
108. 4:16print statements are great to add near
109. 4:18lines of code that you're unclear of or
110. 4:20to print the contents of a variable you
111. 4:23might be having issues with
112. 4:25Roblox studio also has a very useful
113. 4:28debugging tool called Script analysis
114. 4:31you can use this tool by choosing it
115. 4:33from The View tab
116. 4:34the script analysis window performs
117. 4:37static analysis on your scripts and
118. 4:39displays active errors and warnings this
119. 4:42means that instead of having to run your
120. 4:44program to see the errors you can
121. 4:46instantly see any errors in the window
122. 4:48while you're writing your code
123. 4:51Can you spot the error here
124. 4:53the script analysis message says that
125. 4:56hello is an unknown variable this should
126. 4:59actually be the name of the variable
127. 5:01which is message
128. 5:03there we go all fixed and we didn't even
129. 5:06have to run the code to find this error
130. 5:08here's a helpful summary that you can
131. 5:10find in the slide deck or print out
132. 5:12all right let's take what you've learned
133. 5:14and put it into practice