meet it

Quotes turn a number into text.

5 is a number. "5" in quotes is a string that looks like one, and C# treats them very differently. 5 + 3 adds up to 8, but "5" + "3" joins into 53.

Whole numbers go in int boxes. Numbers with a decimal point, like 0.75, go in boxes. Each box only takes its own type, so text in an int box gives error CS0029.

Console.ReadLine() always gives back text. To do maths with it, it first. turns the text "12" into the number 12.

using System;

int apples = 5;
double price = 0.75;
Console.WriteLine(5 + 3);
Console.WriteLine("5" + "3");
Console.WriteLine("Apples: " + apples);
Console.WriteLine(price);
int candles = int.Parse("9");
Console.WriteLine(candles + 1);

int.Parse only works on text that looks like a whole number, so int.Parse("cake") gives an error.

guess first

Two goals and one goal. What is the score?

Guess before you run it. Wrong guesses are how you learn, and nothing is marked.

using System;

string homeGoals = "2";
string awayGoals = "1";
Console.WriteLine(homeGoals + awayGoals);

your turn

Your turn. Look into the future.

Choose how many years ahead to look, as a whole number, and type it in the blank on line 5. We will answer 11 to the question.

Your code

output

press run to see what happens

fix it

Dog years went wrong. Can you fix it?

Broken code to fix

output

press run to see what happens

C# will not multiply on line 5. What type is the box called age?
Console.ReadLine() gives back text, and you cannot multiply text. Convert it into an int first.
Change line 4 to int age = int.Parse(Console.ReadLine());, then press run.

nailed it

you can tell text and numbers apart. :D

Quotes make text, even when it looks like a number.
int holds whole numbers. double holds decimals.
int.Parse turns typed text into a whole number.

new words in your collection

double
convert
int.Parse

This lesson isn’t saved. A free account remembers every lesson you finish.