Python for else loop

[adenn]

Hello today i wanna share about for ...else loop:
example: finding prime numbers
ans = int(input("number:"))
if ans >1:
for i in range(2,ans):
if ans%i==0:
print(f'{ans} is not a prime number')
break
else:
print(f'{ans} is a prime number.')
else:
print(f"{ans} is not a prime number")

What is for else loop?
when for loop hasn't been broke, else will happen

In this case:
I am trying to find prime number, so if ans is larger than 1(to make sure it isn't negative),
i will arrange a for loop, which let the range of 2 to ans(not include ans) to be divided by ans itself
If remaining value can be divided, then it is not a prime number, and the for loop will be break
if the for loop has not been broken, which means nothing can divide ans and get 0 remaining value
then it's a prime number, else will occur and print it's prime number

 

[LTomy]

Hello adenn!

So, if I understand right, your post is a presentation of the for-else loop in Python?

Thank you for sharing your knowledge here!
Just a little remark: Please insert your code inside code tags by clicking on the </> button (And mark it as Python code) and make sure to keep the indentation, especially for Python code 😉

 

[Deleted member 1442]

[CODE lang="python" title="prime.py"]primechecker = int(input("Number please,"))
if primechecker >= 2 or 3 or 5 or 7 or 11 or 13 or 17 or 19 or 23 or 29 or 31 or 37 or 41 or 43 or 47 or 53 or 59 or 61 or 67 or 71 or 73 or 79 or 83 or 89 or 97
print("Your input is a prime number")
if primechecker >= 4 or 6 or 8 or 9 or 10 or 12 or 14 or 15 or 16 or 18 or 20 or 21 or 22 or 24 or 25 or 26 or 27 or 28 or 30 or 32 or 33 or 34 or 35 or 36 or 38 or 39 or 40 or 42 or 44 or 45 or 46 or 48 or 49 or 50 or 51 or 52 or 54 or 55 or 56 or 57 or 58 or 60 or 62 or 63 or 64 or 65 or 66 or 68 or 69 or 70 or 72 or 74 or 75 or 76 or 77 or 78 or 80 or 81 or 82 or 84 or 85 or 86 or 87 or 88 or 90 or 91 or 92 or 93 or 94 or 95 or 96 or 98 or 99 or 100
print("Your input is not a prime number")
print("Script Worked")[/CODE]

Maybe this will work?
@adenn

 

[Ghost]

[CODE lang="python" title="prime.py"]primechecker = int(input("Number please,"))
if primechecker >= 2 or 3 or 5 or 7 or 11 or 13 or 17 or 19 or 23 or 29 or 31 or 37 or 41 or 43 or 47 or 53 or 59 or 61 or 67 or 71 or 73 or 79 or 83 or 89 or 97
print("Your input is a prime number")
if primechecker >= 4 or 6 or 8 or 9 or 10 or 12 or 14 or 15 or 16 or 18 or 20 or 21 or 22 or 24 or 25 or 26 or 27 or 28 or 30 or 32 or 33 or 34 or 35 or 36 or 38 or 39 or 40 or 42 or 44 or 45 or 46 or 48 or 49 or 50 or 51 or 52 or 54 or 55 or 56 or 57 or 58 or 60 or 62 or 63 or 64 or 65 or 66 or 68 or 69 or 70 or 72 or 74 or 75 or 76 or 77 or 78 or 80 or 81 or 82 or 84 or 85 or 86 or 87 or 88 or 90 or 91 or 92 or 93 or 94 or 95 or 96 or 98 or 99 or 100
print("Your input is not a prime number")
print("Script Worked")[/CODE]

Maybe this will work?
@adenn

The main problem with this code is that it can only see if a number is prime for the first 100. It's better to be able to check any number, and generate any range of prime numbers on the fly if needed. I strongly advise against using a static list of numbers like this....

Also, if the first statement is not true, then you don't need the second if there. Just use if - else

 

[Deleted member 1442]

The main problem with this code is that it can only see if a number is prime for the first 100. It's better to be able to check any number, and generate any range of prime numbers on the fly if needed. I strongly advise against using a static list of numbers like this....

Also, if the first statement is not true, then you don't need the second if there. Just use if - else

I tried but still got errors.

 

[Ghost]

I tried but still got errors.

Do you have indents / tabs set up correctly?
Can you share your code with us? I can try to help🙂