The Solution6:14 with James Churchill
In this video, we'll explain the solution to the challenge.
Welcome back, how did you do? 0:00 Don't worry if you weren't able to complete every task. 0:02 It's not unusual to struggle when learning something new. 0:05 Let's walk through my solution. 0:08 For my first task, we need to declare a boolean variable named keepGoing and 0:10 assign it the value of true. 0:15 So, bool for the data type then the name of 0:16 the variable keepGoing=true. 0:21 Next, we need you to define the while loop, to do this we just type the word 0:27 while followed by a set of parenthesis then a code block. 0:32 Inside of the parentheses we need to supply the condition that will be used to 0:39 evaluate if the loop should be executed or not. 0:43 For our situation we just need to provide the boolean variable keepGoing. 0:46 And because we're initializing this variable to true, 0:51 our wire loop will execute at least once. 0:54 Now let's move these to-do comments inside of our loop. 0:57 Be sure not to move the last one. 1:01 That one needs to stay outside of the wire loop. 1:03 I'll press Cmd + X or Ctrl +X to cut. 1:05 Then I'll move my cursor up and then Ctrl+V or Cmd+V to paste 1:10 Just inside of our while loop, we need to prompt the user with the text, 1:20 Enter a number. 1:23 To write text to the console, we can use the Console.Write method. 1:25 We pass into the Write method the text we want to write to the console. 1:31 So, Enter a number. 1:35 Now we need to read the users value and store it in a string variable named entry. 1:39 First the variable, so string entry =, 1:44 then to read the value we use Console.ReadLine. 1:49 Now we need to check to see if the user entered the text quit. 1:55 Sounds like an if statement, so if (entry == 2:00 Then the string literal quit), then a set of curly braces to define a code block. 2:07 I'll move this TODO Exit the program inside of that code block, 2:16 because we only want to do that if this if statement evaluates to true. 2:20 To exit the program, we need to set the keepGoing variable to false. 2:24 Setting the keepGoing variable to false will cause the loop to exit 2:30 on the next go around. 2:34 For our next TODO, 2:35 we want to run this other code, if the user didn't enter the text quit. 2:36 To do that, we can use an else statement, else, and 2:41 then followed by a set of curly braces. 2:45 Then let's move these TODO comments inside of that code block. 2:49 To review, if the entry variable is equal to quit, we will keepGoing to false. 2:54 Else, we will do these other tasks, okay. 3:01 So if the user isn't trying to quite the program, 3:05 we now need to parse the user's entry to an integer. 3:08 Let´s start with our variable, so int for 3:12 the data type followed by the variable name. 3:15 I'll just use number for that. 3:18 To parse a string to an integer, we can use the int data types parse method. 3:21 We pass into the parse method the string that we want to parse, 3:28 in our case that's the entry variable. 3:32 Now that we have a number we can multiply that number by itself 3:36 to determine the square. 3:39 We need another variable, so int result = 3:41 number, and then an asterisk to do multiplication, number. 3:46 So that's number times number. 3:53 And then we store the result in the result variable. 3:56 Now we need to output the result to the console. 4:01 Sounds like a call to the Console.WriteLine method. 4:04 We can use whatever text we want to use here. 4:11 I'll use the second one, so 2 multiply by itself is equal to 4. 4:14 So first, we need to start we the users provided number. 4:18 So I'll use number +, to concatenate number with a string literal. 4:22 Inside of the quotes, we'll type multiplied by itself 4:28 is equal to, then another plus sign. 4:35 Now we need our result, so result. 4:40 Then I'll add another plus sign followed by another set of quotes so 4:43 I can add a period at the end of that sentence. 4:47 For our last task, we just need to output the text Goodbye after exiting the loop. 4:53 So, Console.WriteLine, then the text Goodbye! 4:59 All right, now let's save the file. 5:09 You can do that by pressing Ctrl+S or Cmd+S on the Mac, or 5:11 select the File > Save menu item. 5:15 Now, let's compile and run our program. 5:23 Show the console by selecting the View > Show Console menu item. 5:25 And run the command 5:31 mcs Program.cs. 5:35 Now we can run the program using the command mono space program.exe. 5:40 Here's the prompt asking me for a number ,I'm enter in the number 4. 5:47 And press the Enter, and here is my number squared. 5:51 4 multiplied by itself is equal to 16. 5:55 Let's try another number, how about 6? 5:57 6 multiplied by itself is equal to 36. 6:01 Now I'll type quit to exit the program. 6:04 And we see our message, Goodbye!, and that's it. 6:08 Keep practicing, and we'll see you next time. 6:11
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