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The Solution
6:14In this video, we'll explain the solution to the challenge.
Welcome back, how did you do?
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Don't worry if you weren't
able to complete every task.
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It's not unusual to struggle
when learning something new.
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Let's walk through my solution.
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For my first task, we need to declare
a boolean variable named keepGoing and
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assign it the value of true.
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So, bool for
the data type then the name of
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the variable keepGoing=true.
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Next, we need you to define the while
loop, to do this we just type the word
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while followed by a set of
parenthesis then a code block.
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Inside of the parentheses we need to
supply the condition that will be used to
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evaluate if the loop should be executed or
not.
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For our situation we just need to
provide the boolean variable keepGoing.
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And because we're initializing
this variable to true,
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our wire loop will execute at least once.
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Now let's move these to-do
comments inside of our loop.
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Be sure not to move the last one.
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That one needs to stay
outside of the wire loop.
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I'll press Cmd + X or Ctrl +X to cut.
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Then I'll move my cursor up and
then Ctrl+V or Cmd+V to paste
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Just inside of our while loop,
we need to prompt the user with the text,
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Enter a number.
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To write text to the console,
we can use the Console.Write method.
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We pass into the Write method the text
we want to write to the console.
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So, Enter a number.
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Now we need to read the users value and
store it in a string variable named entry.
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First the variable, so string entry =,
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then to read the value
we use Console.ReadLine.
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Now we need to check to see if
the user entered the text quit.
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Sounds like an if statement,
so if (entry ==
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Then the string literal quit), then a set
of curly braces to define a code block.
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I'll move this TODO Exit the program
inside of that code block,
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because we only want to do that if
this if statement evaluates to true.
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To exit the program, we need to set
the keepGoing variable to false.
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Setting the keepGoing variable to
false will cause the loop to exit
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on the next go around.
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For our next TODO,
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we want to run this other code,
if the user didn't enter the text quit.
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To do that,
we can use an else statement, else, and
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then followed by a set of curly braces.
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Then let's move these TODO comments
inside of that code block.
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To review, if the entry variable is equal
to quit, we will keepGoing to false.
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Else, we will do these other tasks, okay.
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So if the user isn't trying
to quite the program,
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we now need to parse the user's
entry to an integer.
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Let´s start with our variable, so int for
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the data type followed
by the variable name.
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I'll just use number for that.
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To parse a string to an integer, we can
use the int data types parse method.
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We pass into the parse method
the string that we want to parse,
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in our case that's the entry variable.
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Now that we have a number we can
multiply that number by itself
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to determine the square.
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We need another variable, so int result =
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number, and then an asterisk
to do multiplication, number.
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So that's number times number.
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And then we store the result
in the result variable.
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Now we need to output
the result to the console.
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Sounds like a call to
the Console.WriteLine method.
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We can use whatever text
we want to use here.
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I'll use the second one, so
2 multiply by itself is equal to 4.
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So first, we need to start we
the users provided number.
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So I'll use number +, to concatenate
number with a string literal.
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Inside of the quotes,
we'll type multiplied by itself
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is equal to, then another plus sign.
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Now we need our result, so result.
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Then I'll add another plus sign
followed by another set of quotes so
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I can add a period at
the end of that sentence.
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For our last task, we just need to output
the text Goodbye after exiting the loop.
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So, Console.WriteLine,
then the text Goodbye!
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All right, now let's save the file.
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You can do that by pressing Ctrl+S or
Cmd+S on the Mac, or
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select the File > Save menu item.
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Now, let's compile and run our program.
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Show the console by selecting
the View > Show Console menu item.
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And run the command
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mcs Program.cs.
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Now we can run the program using
the command mono space program.exe.
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Here's the prompt asking me for
a number ,I'm enter in the number 4.
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And press the Enter, and
here is my number squared.
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4 multiplied by itself is equal to 16.
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Let's try another number, how about 6?
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6 multiplied by itself is equal to 36.
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Now I'll type quit to exit the program.
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And we see our message,
Goodbye!, and that's it.
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Keep practicing, and
we'll see you next time.
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