Coding Practical $4$

Problem Statement: You are building an application that allows registered users to

create a pie chart or a line graph.

Before You Begin

$1.$ Create an m$-$file with the filename lastName$\_$Prac$4.$m$.$

$2.$ No variable names are provided but you are expected to name all necessary

variables according to the rules and conventions discussed in class.

$3.$ Download the UserDatabase.txt file.

a$.$ This is the file you will use to store all usernames and passwords. The

usernames and passwords are separated by a space.

$4.$ This practical is your chance to apply all of the concepts that we have went over

throughout the semester. If your code is substantially similar to another student$$s$,$

you will be given a zero. If you use outside sources, they must be cited.

Getting Started

$$ Include header comments formatted as show below, using your own name and

ID number. Failing to include the honor code or your name will result in a zero.

Failing to provide the other information in the header will result in a point

deduction.

$\%$ CSCI $251,$ Section X

$\%$ YOUR NAME

$\%$ Student ID $12345678$

$\%$ Coding Practical $4$

$\%$ Today$$s Date

$\%$ In keeping with the Honor Code of the School of Engineering, I certify that the

following work is substantially the result of my own efforts.

Program

For each unified block of code add a comment explaining the code $($doesn$$t have to be

multiple sentences but step $3$ or step $4$ isn$$t detailed enough$)$

$1.$ Include the commands to clear the workspace and command window.

$2.$ Prompt the user to enter whether they would like to sign up or login$.$

a$.$ Standardize the output by converting the input to all uppercase or

lowercase letters using a pre$-$defined function of your choice.

$3.$ Programmatically open the UserDatabase.txt file.

a$.$ You will be reading from and writing to the file. Also, you do not want to

recreate the file each time it is opened.

$4.$ Using an I$/$O function of your choice, create an array of the usernames and a

separate array of the passwords within the userDatabase.txt file.

a$.$ The lab $8$ starter code shows a quick and easy way of doing this.

$5.$ Check if the user entered sign up$.$

$6.$ If the user selected sign up$,$ prompt them to enter a username with at least four

characters and no spaces.

$7.$ Create a user$-$defined function that checks if the username is invalid $($has less

than four characters and or spaces$).$

a$.$ The user$-$defined function should use the username entered by the user

as the input argument and a logical variable representing whether the

username is invalid as the output argument.

$8.$ Call the user$-$defined function from step $7$ and assign it to an actual output

argument.

$9.$ Create a user$-$defined function that checks if the username already exists within

the array of usernames you created in step $4.$

a$.$ The user$-$defined function should use the username entered by the user

and the array of usernames as the input arguments and a logical variable

representing whether the username is new as the output argument.

b$.$ To check if the username already exists iterate the array of usernames

and check if each username within the array is the same as the username

entered by the user. Once you find the username already exists you no

longer need to continue to iterate $($there is a statement that terminates the

loop completely$)$ and can assign a value to the output argument

accordingly.

$10.$Call the user$-$defined function from step $9$ and assign it to an actual output

argument.

$11.$Using the values returned from the function calls in step $8$ and $10,$ create a while

loop that continues to re$-$prompt the user for a username until it is valid and

doesn$$t already exist.

a$.$ Structure the loop condition properly. Remember the while loop will

continue to iterate until the condition returns false.

$12.$Below the while loop from step $11,$ prompt the user to enter a password with at

least six characters and no spaces.

$13.$Create a user$-$defined function that checks if the password entered is valid $($at

least six characters and no spaces$).$

a$.$ The user$-$defined function should use the password entered by the user as

the input argument and a logical variable representing whether the

password is invalid as the output argument.

$14.$Call the function from step $13$ and assign the returned value to an actual output

argument.

$15.$Using the values returned from the function call in step $14,$ create a while loop

that continues to re$-$prompt the user for a password until it is valid.

$16.$Below the while loop from step $15$ print the statement New user created.

$17.$Using an fprintf function, write the new username and password to the

UserDatabase.txt file.

$18.$Prompt the user to indicate if they would now like to login by entering yes or no$.$

a$.$ Standardize the output by converting the input to all uppercase or

lowercase letters using a pre$-$defined function of your choice.

$19.$If they enter yes, reassign the variable from step $2$ to the character vector login$.$ If

they enter no$,$ use a return statement to end the program.

$20.$Check if the variable from step $2$ is assigned l