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Welcome back.

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Now, let's move on to the second stage where we're gonna create our function to

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log in an existing user.

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What I'm gonna do is I'm gonna push the function here all the way down to the very end

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and outside. Let's

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add a new notes that says function to log in the user.

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So

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what do we need? Let us first of all, create the name of the function that will be de

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let's say login underscore user

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and let's add a colon.

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So what are we going to need? We're going to need both the username and the password.

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So

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let us say username

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equals and now input, we're going to prompt the user to provide

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their username. So

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enter your username.

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Ok. Call on, let's add

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some space right there.

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Ok.

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Next will be the password, right? So I'm gonna say password

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equals and then

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enter your password pretty straightforward.

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We're going to have to now check to see if the username actually matches the password

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that we had in the

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registration section. So

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I'm going to add my note real quick

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check to see if username and password match. Ok. So how do we do this, the good old if

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and now username

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and user

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on the

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core.

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Oops, sorry about that

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in us.

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So if username in user credentials and

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because both username and password have to be checked

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and user

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underscore credentials

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and now the brackets

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username

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equals to the password.

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All right.

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So this is what we did here.

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We're checking to make sure that if the username

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that's already been stored in the dictionary user credentials

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and now

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the key value pair for the username and password, if they actually match,

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then we can print.

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All right, I'm gonna say print,

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let's just say, welcome back.

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All

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very, very,

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very simple.

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If it's not a match,

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we can print

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now, we can say

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uh invalid username and password, please try

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again.

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All right.

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And there it is pretty straightforward.

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So what I'll do right now is I am going to call both of the functions, register user

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and then also

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uh log in underscore user.

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However,

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we need to pay very close attention to the fact

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that the loop currently resides inside of the register function.

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It is not outside.

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So we need to run our loop independently of the register function and

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the login function. So what I'll do is I am going to cut out

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the while true,

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cut it out.

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OK?

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And then

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I am going to paste it

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outside

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on its own

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while true. However, everything else

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must fall

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under it. So I'm going to table it

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everything on there.

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Uh Let me do this again

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and there you go. So there, so there it is.

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So you can see right now that the user credentials

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and then the wire loop are outside the independent.

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Now the wild should the entire loop begins with

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registering the user

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and then logging in the user checking to see if there are matches, things like that.

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So this should work. I'm going to go ahead right now to run the program

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and let us see. So

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I'm going to provide the first username.

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Let's go with Mark and then password will be admin

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for

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successful. Now let us try to log in

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as mark. So I'm gonna say mark and then admin.

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So mark and then admin

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and there you go. Welcome back. It works successfully.

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Now it's gone back to the registration phase.

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If I try to now create another account with Mark,

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it's going to say username already exists. Please choose a different username.

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Let's go with Nancy. Ok, password for Nancy.

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Let's go with password.

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Ok. And now you can see it says sorry, any valid user name pass. Please try again

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the reason why this happens because

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the way the program is written out right now,

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it simply goes step by step by step by step regardless of whether or not

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the previous step was successful.

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So over here, you can see it set off with the registration phase

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that worked, it then moved on to the login phase that worked.

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It now came over here for the login phase again.

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Oh,

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sorry for the registration phase again. It saw that mac already exists as a user.

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So it said please choose a different username. However,

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it skipped

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asking the user to create another username over here.

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It went straight to the login phase where it checks to see if Nancy existed.

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NSA

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did not exist. That's why it said invalid

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name. A Puzo. Please try again.

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So right now it has gone back to the registration phase. So

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if I say Nancy again,

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now you can see it's asking Nancy for the password because it's in

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registration phase.

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Now, if I type in admin,

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it says we

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successful. Now let us try logging in because now I was going to the login phase.

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I say Nancy,

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Nancy's password is admin,

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but I'm gonna type in something different enter and

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then it says invalid user name or password.

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Please try again.

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So

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we can see right now that the program works kind of like 80%

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the registration phase, the login phase work. However,

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if we were to ideally

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when we're trying to create a new user account,

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and if we are trying to use a username that already exists,

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the program should not move on to the second stage, which is to log in the user until

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the user has actually provided a brand new user name for the registration.

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We're gonna fix that

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in the third and final part of this assignment.