i dont understand python exeptions

Question

i understand exceptions and i dont really understand the use except debugging but, i dont understand what raising does and what its for thanks for the help :)

Answer 1

Exceptions are errors. Since there are different types of exceptions, when one happens in your code you’ll know what’s wrong and how to fix it. For example:

inp = input()
x = int(inp)

Here, you’re expecting an int as input. But the user may enter a non-numeric value, like “hello”. Then the int() function will raise a ValueError exception. This will let you know what went wrong.

Another thing is the raise statement. Here you’ll raise an exception yourself. This can be useful if you’re making a long code for other people to use, and want them to know if they’re doing something wrong. For example:

m = input(“Enter mass: “)
mass = float(m)
if mass < 0:
raise ValueError(“A mass must be a positive number”)

Answer 2

in the lesson: raising exceptions i also dont understand this:
Exceptions can be raised with arguments that give detail about them.
For example:
name = "123"
raise NameError("Invalid name!")
Try It Yourself

Result:
>>>
NameError: Invalid name!

Answer 3

I had a problem with exceptions and especially "raise statement" too. what I understand ...

In general, you coding in a usual structure:
***************************
1- Try:
2- ....
3- except ValueError:
4- ....
5- except Exception:
6- ....
7- else:
8- ....
9- finally:
10- ....
*************************
- The code first run "Try statement".
- If there were any Errors, it refers to "except" lines. (line 3 or 5 in this example)
- If there wasn't any Error, it refers to line 7.
- Without considering there was Error or not in Try statement, "finally" statement run at the end.

But When you want manually run an exception, you can use raise.
for example in below code, after line 3 the code goes line 6 for run "Exception" that has said in line 3.
***********************
1- Try:
2- ....
3- raise Exception
4- except ValueError:
5- ....
6- except Exception:
7- ....
8- else:
9- ....
10- finally:
11- ....
*************************
For more details:
I saw below video and I think this video can help about exceptions, raise and finally:

https://www.youtube.com/watch?v=NIWwJbo-9_8

Answer 4

exceptions are Not An Error, they are way to process situation in special way, out of usual sequence of statement flow. Thouse situations are predicted, awaited and kindly handled, so exceptions are AntiErrors. Exceptions just a way to avoid tons of Ifs in code, and add some call stack logic, already known from old times as handler registration

Answer 5

Reza Kheyrandish nice video tutorial....really helped..

Answer 6

ohh so raising is to make sure what the input is will be logical or what you want thanks

Answer 7

what i understand it means ....we are predetecting the error before being the file run

Answer 8

so thanks for all your replies........... but please help me with the output , in the sense what should we type in the space given after the question asking for the output