class2-prep

Module 2

Prep for Class 2

Before coming to Class 2, please work your way through the following material:

Lecture

Task	Resource Type	Link	Instructions
Watch	Lecture	Week 2, continued	Watch the week's second lecture, with Rob Bowden filling in for David.

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Strings, Under the hood

Task	Resource Type	Link	Instructions
Read	Lecture Notes	Week 2, continued / More on Strings	Review the notes on the first part of the lecture about strings. Stop at the Arrays header.
Read	Resource	Custom strlen	A from-scratch implementation of the strlen function, to help illustrate how to write your own function, and give some insight into the chars that make up strings

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Arrays

Task	Resource Type	Link	Instructions
Read	Resource	Array Basics	A quick runthrough of array syntax basics: how to declare, read, write
Watch	Doug's Playlist	Arrays	Doug talks about arrays, an important data structure.
Follow-Along	Walkthroughs	ages	Follow David to create a program that uses an array to get the ages of everyone in a room. You can grab the pseudocode here.
Do	Exercise	Can You Vote?	Write a program to read through an array of peoples' ages and outputs whether or not they are old enough to vote.
Read	Lecture Notes	Week 2, continued / Arrays	Read through the notes on "Arrays", which will review the ages program you recently wrote.
Watch	Shorts	Arrays	This short will talk about when to use an array, and how to implement one. Rob talks about "pointer arrays" and malloc - don't worry about this for now.

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Command-Line Arguments

Task	Resource Type	Link	Instructions
Read	Lecture Notes	Command-Line Arguments	Read the section titled "Command-Line Arguments". We'll be using these in Problem Set 2. Stop when you get to the Cryptography header.
Follow-Along	Walkthrough	argv-0	Follow David to create a program that takes command-line arguments. You can grab the pseudocode here.
Follow-Along	Walkthrough	argv-1	Continue working on this program to make it print out all of the command-line arugments we get from the user. You can grab the pseudocode here.
Do	Exercise	Argv With Indexes	Practice accessing the command line arguments by indexing into argv
Do	Exercise	Previous	Use a new function called atoi() to fix a broken code example.
Watch	Doug's Playlist	Command-Line Arguments	Doug reviews command-line arguments in more depth.
Do	Exercise	Command-line Calculator	Extend the ideas you learned in Adder and argv-0 to add numbers that the user provides on the command line.
Follow-Along	Walkthrough	argv-2	Return to the argv program and follow David to make it print out all of the individual characters from the command-line arugments. You can grab the pseudocode here.
Watch	Shorts	Command-Line Arguments	Watch this short that talks more about command-line arguments, argc, and argv.
Study	CS50 Study	Command-Line Arguments	If helpful, you can test and review your knowledge of command-line arguments using CS50 Study.

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Magic Numbers, Global Variables

Task	Resource Type	Link	Instructions
Watch	Shorts	Global Variables	Joe introduces the concept of the global variable, which is a variable that is not limited to a local scope, like the normal "local" variables we have been using so far.
Watch	Doug's Playlist	Magic Numbers	Doug introduces the concept of "magic numbers", explaining why we want to avoid them and how we can do so.
Read	Resource	Magic Numbers	Look over an example program that eliminates its magic numbers while avoiding the danger of global variables.

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Now you're ready for Class 2!