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For the 2018-2019 school year, we have switched to using the WLMOJ judge for lesson information, no new lessons will be added here.

In this lesson, we will be focusing on the syntax of using variables.


Turing

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var firstName : string := "Vincent"
var lastName : string := "Macri"
var languages : int % In Turing, you can declare a variable, and give it a value later.
languages := 3

put(firstName + " " + lastName + " made this lesson. It teaches variables in " + intstr(languages) + " languages!")

Python

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firstName = 'Vincent'
lastName = 'Macri'
languages = 0 # Python doesn't let you declare local variables without assigning them.
languages = 3 # But you can always just assign a new value when you are ready.

print(str.format("{} {} made this lesson. It teaches variables in {} languages!", firstName, lastName, languages))

Java

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String firstName = "Vincent";
String lastName = "Macri";
int languages; // In Java, you can declare a variable, and give it a value later.
languages = 3;

System.out.println(firstName + " " + lastName + " made this lesson. It teaches variables in " + languages + " languages!");

You may have noticed that Turing and Java use double quotes (" ") for strings, while Python uses single quotes (' '). In Turing and Java, double quotes are used for strings, while single quotes are used for single characters. In Python, you can use either double or single quotes, but Python programmers tend to prefer single quotes.

For Turing and Java, we concatenated the variables with the string. Concatenate is a fancy word for put together.

In Python, we used the str.format() command. It formats strings for us. We use {} in place of the variables, and then list the variables in order at the end.

Practice

The following programs require user input. If you don’t know how to get user input yet, write your programs so that you can easily change the initial values of the variables instead of prompting the user for input.

Write a program where the user can enter their first name, last name, and age, and then output “first name last name is age years old.”

Write a program where the user can enter two numbers, and then output the sum of the numbers.