Flowchart for the Factorial Program

Flowchart for the factorial program.

One thing you'll hear or see referred to a lot

is something called a flowchart

either in computer science, so really when people

talk about any type of algorithm or process.

So what I thought I would do

is for every program I write, is do a simple flowchart

maybe I won't do it for every one,

but I'll start with one of the basic ones,

just so we understand that a flowchart isn't anything fancy.

So in this factorial program that we had been looking at in the past couple videos

Any flowchart you're just going to be at a starting point

I guess, depicted with a circle or oval of some kind.

And so we start at this line above this assignment

of the number where we actually ask for input from the user.

And then after that, we ask for input from

the user. This line right here.

We are asking for input from the user.

So this right over here

And we will depict that by a parallelogram.

And that is input from the user.

And then we'll just say number

equals user input.

And you can be a little bit loosey-goosey with the terminology

here, you're really just trying to tell us what you're doing in this step.

The parallellogram tells us that we are somehow interfacing with the user.

We're either taking something from the user or we're outputting something to the user.

So here, we're saying user input is equal to number.

We're assigning number to user input.

Then, the next thing we do is just a straight up operation.

We just set product to be equal to 1

And there we just do that in a rectangle.

Product equals 1.

Product is equal to one.

And then, something interesting is going to happen.

We enter into our for loop.

And we start with, and what I'm going to do here

is I'm going to write it a little bit different than we wrote it over here.

So we do is we start a

What we are doing is

We are going to start our for-loop

essential with an assignment

Where we assign

For loop is really a bunch of things

Happening at the same time

It assigns "i" to the first number in the sequence

or it tests whether it can assign "i" to the first number in the sequence

if it can

then it proceeds

if it can't

then it breaks out of the for-loop

so let me put it this way

i will do kind off a test case

right over here

So items left in sequece

so item left

in sequence

and when I'm referring to the sequence I'm talking about

this sequence over here

the range of our number

in the example i gave in the last video

the number was "3"

so items left in this sequence

i know it's hard to read

right over here

If there are, so lets say that there are

items left in the sequence

so if there are items left in the sequence

so we'll just say

"i" is equal to next item

"i" is equal to next

"i" is euqal to the next item

if there are

well i'll just hold off for the case

where there are no items left in the sequence

but lets say that there are

"i" is equal to the next item

and then we also define

we define "product"

to be

we define "product"

actually i wanted to do these in blue

just our regual

or regular

se let me write this

is "YES"

if there are items in the sequence

then "i" is equal to the next item

is equal to the next item

thats one operation we do

and then we reset "product"

we reassign "product" to be equal to

what the former value of the "product" was

times "i" plus 1

and at this point

we essentially loop back

to this test over here

so at this point

we loop back

i'll try to write it neatly

we loop back to

we loop back to this point in the program

that's why it is called a loop!

cause after you preform this operation

this is in bedded in the loop

you go back to the beginning

to see if there is any more of the loop to do

so you go

back to the beginning before the loop and say

"hey, are there any items in the sequence"

and this should be a question mark over here

these kind of question mark decision points

are usually specified with this diamond

if there is another item in the sequence

then "i" is equal to the next item and "product" is

equal to what "product" was times "i" plus one

we go to the next

"are there items left in the sequence?"

and at some point there won't be any items

left in the sequence

so there won't be, at some point there won't be

items left in the sequence

and we can go to the right or i'll just break out of it down here

and now we have broken out of this for-loop

we have boken out of this for-loop

and then the next thing we do

once we are done with our for-loop

is we just print the value of "product"

we just output the value of "product"

so that is an interaction with the user

so we are literally just outputting the value of "product"

so we output

output "product"

and we are done!

and i can write end

for the end of our program

and the program will stop running

end

so this is just a simple flowchart for this simple program

and hopefully it helps you appreciate

that one little understanding of the program

itself if the last two videos didn't help too much

and also gives you a simple understanding

of how to write a flowchart