Strings
1. 2. 3. 4.
Open Visual Studio Code At the top click on View->Integrated Terminal (if not already open) In the terminal, first run: npm run pull After this finishes run: npm start
Strings Lecture 05
“No Strings Attached”
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
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)
Recap - Variables • Variables are places in memory where data can be stored • Two steps: 1. Declaration – reserve a spot in memory • let : ;
2. Assignment – give some variable a value • = ;
*The very first assignment of a variable is known as initialization
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”
String Rules • We’ve worked with strings already! print(“Welcome to the COMP101 Calculator”);
• Strings are denoted by double quotes • Variable declaration • let : ;
• let day: string = “Wednesday”; • print(day); • print(“day”);
• Typescript is case sensitive! String ≠ string
Types • In Typescript we must explicitly specify the type of data our variable will hold during declaration • let : ;
• 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”;
+ • 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?
+ 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
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”);
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!***
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 ” 4. Print out a compliment, also including the name of the user • Ex. “ is A++!”
5. Check in on Poll Everywhere when finished!
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
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.
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!
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!
Open Visual Studio Code At the top click on View->Integrated Terminal (if not already open) In the terminal, first run: npm run pull After this finishes run: npm start
Strings Lecture 05
“No Strings Attached”
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
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)
Recap - Variables • Variables are places in memory where data can be stored • Two steps: 1. Declaration – reserve a spot in memory • let : ;
2. Assignment – give some variable a value • = ;
*The very first assignment of a variable is known as initialization
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”
String Rules • We’ve worked with strings already! print(“Welcome to the COMP101 Calculator”);
• Strings are denoted by double quotes • Variable declaration • let : ;
• let day: string = “Wednesday”; • print(day); • print(“day”);
• Typescript is case sensitive! String ≠ string
Types • In Typescript we must explicitly specify the type of data our variable will hold during declaration • let : ;
• 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”;
+ • 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?
+ 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
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”);
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!***
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 ” 4. Print out a compliment, also including the name of the user • Ex. “ is A++!”
5. Check in on Poll Everywhere when finished!
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
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.
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!
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!
