Python: Default Arguments
Let's look at the
round() function, which rounds the number passed to it:
result = round(10.25, 0) # 10.0
We passed two parameters to it:
- Number to be rounded
- Rounding accuracy
0 means that the rounding will be to an integer value. More often than not, you need to round to a whole number, not to two, three, four etc. decimal places. So the creators of the
round function made the second parameter unnecessary and gave it a default value of
0 inside the function. So, you can choose to not specify the second parameter and the result will be the same:
result = round(10.25) # 10.0
And if you need a different precision, you can pass a parameter:
# rounding to one decimal place result = round(10.25, 1) # 10.2
If a function in Python accepts optional arguments, they always come after the mandatory ones. There can be any number of them. It depends on the function itself, but they always go next to and at the end of the list of arguments.
Round up the number written in the
number variable to two decimal places and print the result on the screen.
The exercise doesn't pass checking. What to do? 😶
If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:
- Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨
Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.
My code is different from the teacher's one 🤔
It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.
In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.
I've read the lessons but nothing is clear 🙄
It's hard to make educational materials that will suit everyone. We do our best but there is always something to improve. If you see a material that is not clear to you, describe the problem in “Discussions”. It will be great if you'll write unclear points in the question form. Usually, we need a few days for corrections.
By the way, you can participate in courses improvement. There is a link below to the lessons course code which you can edit right in your browser.
Default setting optional function parameter