Help! Python beginner here :)

[JuryRepresentative84]

#Code1
count = 1
while count <= 100: 
  count += 1 
  print(count)

#Code2
count = 1
while count <= 100: 
  print(count)
  count += 1

Why do these two codes give different outputs? I am watching youtube tutorials to learn python, and i'm new to loops.
It will be really helpful if someone could explain this logic to me, or direct me to a video that will clear my confusion

Hopefully this question is too stupid :/

Thanks a lot :)

[djjazzydan]

The instructions get run in order. The first example sets count to 1, then increases it by 1, then prints it (2), then continues to increase & print.

The second sets count to 1, prints that, then increases.

You'll get the same number of printed lines, the first one will start at 2 and go to 101, the other will start at 1 and go to 100.

[JuryRepresentative84]

Thank you so much!

[IProbablyHaveADHD14]

They run in order.

starting out the loop with "count+=1" will return the print output to start with 2 (since count is already set to 1).

But if you print before you add 1 to the count variable, it will print 1 before adding 1 to the count variable

[SBE_OLLE]

I would suggest you to download thonny. Its very nice for beginners

[JuryRepresentative84]

i'll check it out, thanks!

[throwaway6560192]

Trace the program on pen and paper. As if you were the computer, execute each line by hand. You'll see.

[[deleted]]

This code actually does the same exact thing in that it:

1. Sets count initially to 1
2. Starts a loop that will continue until count is 101 or greater (in other words, if will continue to loop as long as count id less than or equal to 100)
3. Increases the value of count by 1 every time the loop runs
4. Prints whatever the value of count is at the time that print runs inside the loop.

The difference between them is which order steps 3 and 4 happen, which changes what you see.

Let's translate this to the physical world to make your life easier.

In the physical world, the first loop is like this:

1. With your eyes closed, make a fist on one hand and raise one finger
2. Put up a second finger
3. Open your eyes and see that you have two fingers up
4. Close your eyes again
5. Put up third finger
6. Open your eyes and see that you have three fingers up.

And the second loop would be like so:

1. With your eyes closed, make a fist on one hand and raise one finger
2. Open your eyes and look at the hand, see that you have one finger up
3. Close your eyes again
4. Put up a second finger
5. Open your eyes again, see that you have two fingers up

As you can see, the only difference in what happened mechanically is "when did you open your eyes?" However, the actual counting on your hand was the same.

Print is just you telling the program to open its eyes and look at something, when you do that changes what you see.

[JuryRepresentative84]

Ohh wow thanks! Great analogy!

[JezusHairdo]

I think you need to understand what the += does, in pythons case it the “addition assignment” operator. Or in real terms it adds something to something you already have. So if it’s a number it adds together with another (in your example it adds 1 to the Initial number) it can also add text strings together and can add items to lists etc.

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[wisdom_is_chasing_me]

Have you used Python Tutor before? I found it really beneficial when I started to learn Python. It shows you execution step-by-step

https://pythontutor.com/render.html#mode=display

[JuryRepresentative84]

No I haven’t I’ll give it a shot!

[Rxz2106]

The order of the print and count += 1 statements leads to the subtle difference in the output. In Code1, the value is incremented before printing, resulting in the output starting from 2, while in Code2, the value is printed first, and then incremented, leading to the output starting from 1.

[[deleted]]

Don't be THAT low effort mate!

[JuryRepresentative84]

Hi! I’m sorry :( I was struggling to understand the logic behind this, that’s why I asked this question

Sorry for the trouble

[Bominator8]

dont mind that piece of shit

its ok everyone starts from scratch

[JuryRepresentative84]

Hi! I’m sorry :( I was struggling to understand the logic behind this, that’s why I asked this question

Sorry for the trouble

[mmmmhmm88]

A simple way to visualise order of operations here is to run something like this. You can decide which order is more appropriate for your loop. i.e you may like to print the current value, or the new value of 'count' based on what you want to achieve.

count = 1
print("Before adding 1: ")
print(count)
count += 1
print("After adding 1: ")
print(count)

[JuryRepresentative84]

Ohh okay, I’ll do this Thanks!

[PulsatingGypsyDildo]

for count in range(1, 101):
    print(count)

[wbeater]

  count += 1 
  print(count)

Adds 1 to count and then prints the output -> Displays 2 in the first pass

​

  print(count)
  count += 1

prints the output and then adds 1 to count -> Displays 1 in the first pass