Methods Lab

Lab Objectives

• Practice creating methods
• Reinforce the three common iteration patterns
• Introduce Namespaces

Practice

In your pairs, you will work through the following exercises. As you work through the exercises, take turns being the person typing out code. For example, Partner A will share their screen and typing code into their Repl for the first exercise; Person B will be helping direct Person A with what they should type. Then, for the next exercise, switch roles. Repeat until you work through all of the exercises. This should be a collaborative process!

For the first three exercises, both partners will fork this REPL.

Exercise 1 Create a method called Downcase() that takes a list of strings as an argument, and returns a list of those strings downcased. The method should be able to be called like this:

var names = new List<string> {"Alice", "Bob", "Charlie"};
var lowerNames = Downcase(names);

Console.WriteLine(String.Join(", ", lowerNames));
//Output -> alice, bob, charlie

Exercise 2 Create a method called GetTwoDigitNumbers() that takes a list of integers as an argument, and returns a list of only the numbers that have 2 digits. The method should be able to be called like this:

var numbers = new List<int> {1, 8, 19, 21, 29, 31, 99, 102, 145};
var twoDigitNums = GetTwoDigitNumbers(numbers);

Console.WriteLine(String.Join(", ", twoDigitNums));
//Output -> 19, 21, 29, 31, 99

Exercise 3 Create a method called CountFourLetterWords() that takes a list of words as an argument, and returns an integer that is the count of words in that list that have 4 characters. The method should be able to be called like this:

var words = new List<string> {"bake", "bark", "corn", "apple", "wart", "bird", "umbrella", "fart"};
var countOfFourLetterWords = CountFourLetterWords(words);

Console.WriteLine(countOfFourLetterWords);
//Output -> 6

For the next three exercises, we only want you to pseudo-code what the method might look like. You do not need to implement the code. Really think about what needs to happen during each iteration, and what values you have access to at any given point. We will revisit these three exercises later in the week!

Exercise 4 Pseudocode a method called SumSecondNumbers() that takes a multidementional array as an argument, where each element is an array of 2 integers, and sums the second integer of each sub-array. You may want to take a look at this resource to help you get started. If implemented (you don’t need to do that today!), the method should be able to be called like this:

int[,] numberPairs = { { 1, 2 }, { 2, 3 }, { 3, 4 } };
int sumOfSecondNums = SumSecondNumbers(numberPairs);

Console.WriteLine(sumOfSecondNums);
//Output -> 9

Exercise 5 Pseudocode a method called NormalizeZipCodes() that takes an array of integers as an argument, and returns an array of stringified versions of those integers as zip codes.
*A note on zip codes: All zip codes are 5 characters long; if an integer zip code is fewer than 5 digits, we should add as many 0s to the front of that number as we need to reach 5 characters. So, a given integer zip of 525 would be normalized into "00525". If implemented (you don’t need to do that today!), the method should be able to be called like this:

var zipCodes = new[] {80228, 5031, 2112, 52556, 515 };
string[] result = NormalizedZipCodes(zipCodes);

Console.WriteLine(result);
//Output -> 80228, 05031, 02112, 52556, 00515

Exercise 6 Pseudocode a method called GetWordsByFirstLetter() that takes two arguments: a character, and a list of strings. The method should return a subset of the given list that contains all the words that start with the given character. If implemented (you don’t need to do that today!), the method should be able to be called like this:

var words = new List<string> {"weirdo", "quill", "fast", "krill", "quaint", "quieter", "koala"};
var qWords = GetWordsByFirstLetter('q', words);
var kWords = GetWordsByFirstLetter('k', words);
var jWords = GetWordsByFirstLetter('j', words);

Console.WriteLine(qWords);
//Output -> quill, quaint, quieter

Console.WriteLine(kWords);
//Output -> krill, koala

console.WriteLine(jwords);
//Output -> 

Keep an eye on slack We will come back together as a group to share some of the code we have been working on!