npm run pull npm start

Transcription

1 1. Open Visual Studio Code 2. At the top click on View->Integrated Terminal (if not already open) 3. In the terminal, first run: npm run pull 4. After this finishes run: npm start Strings Lecture 05 No Strings Attached

2 Announcements PS1 releasing this afternoon Split into 3 parts: walk, jog, sprint Start early!!!!!!!!!!!!!!! Will take significantly longer than PS0 Office Hours in Sitterson 008 Mon-Thurs 10am-8pm, Fri 10am-6pm, Sun 12pm-5pm Quiz on Friday Come to tutoring! Thurs 2-6PM in Sitterson 115

3 Warm-up let foo: number = 1; let bar: number = foo + 7; let baz: number = bar foo * 2; baz = baz + 1; print(baz); What is the value printed to the screen? (Submit answer on Poll Everywhere)

4 Recap - Variables Variables are places in memory where data can be stored Two steps: 1. Declaration reserve a spot in memory let <name>: <type>; 2. Assignment give some variable a value <name> = <value>; *The very first assignment of a variable is known as initialization

5 Introducing: Strings So far, we have only used variables to manipulate numerical data Other data types are common in programming Strings textual data A string of characters

6 String Rules We ve worked with strings already! print( Welcome to the COMP101 Calculator ); Strings are denoted by double quotes Variable declaration let <name>: <type>; let day: string = Wednesday ; print(day); print( day ); Typescript is case sensitive! String string

7 Types In Typescript we must explicitly specify the type of data our variable will hold during declaration let <name>: <type>; The type of the data being stored must match the type of the variable let temp: string = four ; let temp: string = 4; let temp: string = 4 ;

8 + We ve already seen how to add two numbers in Typescript let num1: number = 5; let num2: number = 7; let num3: number = num1 + num2; print(num3); // prints 12 The + operator can also be applied to strings What does it mean to add strings?

9 + with Strings (String Concatenation) Same syntax as working with numbers, different outcome let first: string = Jeffrey ; let last: string = Young ; let name: string = first + last; print(name); Concatenation combining one or more things

10 String Concatenation We can also concatenate strings and numbers + will only perform addition if used with two numbers Can perform multiple concatenations in a single line Processed from left to right let age: number = await promptnumber( How old are you ); print( You are + age + years old );

11 promptstring We can similarly prompt a user for string input let dayofweek: string = await promptstring( What day is it ); let dayofweek: number = await promptstring( What day is it ); ***Always double check that types match!***

12 Hands-On: Compliment Generator We are going to make a compliment generator! 1. Open 00-compliment-app.ts inside the lec05-strings folder 2. Prompt the user for their name and store this in a variable called name let name: string = await promptstring( What is your name? ); 3. Use string concatenation to print out: Welcome <name> 4. Print out a compliment, also including the name of the user Ex. <name> is A++! 5. Check in on Poll Everywhere when finished!

13 VSCode Errors One error in your code prevents the program from running! Similar to Word, you ll see a red underline where VSCode thinks the error is Just like Word, this isn t always perfect You will also see this error message in the browser Line number where error occurs

14 Variable Naming The name of a variable can be anything you want Typically, as programmers we name the variable something that will clue us in as to the purpose of that variable Especially useful as programs grow larger Rules: 1. Must not start with a number 2. Cannot contain spaces 3. Cannot contain a special character other than _ Convention 1. For multi-word variables use camelcase dayofweek, conversionrate, heightininches, etc.

15 Hands-on: Mad Libs (Part 1) 1. Open 01-mad-libs-app.ts inside the lec05-strings folder 2. Prompt the user for a positive and negative adjective using two promptstring statements. Store these in two variables named positiveadj and negativeadj 3. Prompt the user for a violent verb. Store in a variable named verb 4. Prompt the user for a large number and a small number using two promptnumber statements Store these in two variables named uncscore and dookscore 5. Compute the difference of these two variables and store in a third variable called winby 6. Run your code to make sure the prompts work and then check in on Poll-Everywhere. Our game is halfway complete!

16 Hands-on: Mad Libs (Part 2) 1. Declare a string called madlib1 and initialize it by concatenating the positive adjective "On February 9th, the " + positiveadj + " UNC basketball team" 2. Declare a string called madlib2 and initialize it by concatenating the verb and the negative adjective " is going to " + verb + " the " + negativeadj + " Dook team" 3. Declare a string called madlib3 and initialize it by concatenating winby variable " and win by " + winby + " points!" 4. Declare a string called finalmadlib and assign it the concatenation of madlib1, madlib2, and madlib3 5. Print your finalmadlib!! 6. Check in on Poll Everywhere when finished!