Questions
Find answers to frequently asked development questions. For information about Better Stack products, explore our docs.
How do I pass a variable by reference in Python?
In Python, variables are passed to functions by reference. This means that when you pass a variable to a function, you are passing a reference to the memory location where the value of the variable...
What does ** and * do for parameters in Python?
In Python, the * symbol is used to indicate that an argument can be passed to a function as a tuple. The ``** symbol is used to indicate that an argument can be passed to a function as a dictionary...
How do I check if a list is empty in Python?
You can check if a list is empty by using the len() function to check the length of the list. If the length of the list is 0, then it is empty. Here's an example: my_list = [] if len(my_list) == 0:...
How do I concatenate two lists in Python?
You can concatenate two lists in Python by using the + operator or the extend() method. Here is an example using the + operator: list1 = [1, 2, 3] list2 = [4, 5, 6] list3 = list1 + list2 print(list...
How can I add new keys to Python dictionary?
You can add a new key-value pair to a dictionary in Python by using the square brackets [] to access the key you want to add and then assigning it a value using the assignment operator =. For examp...
What is init.py for?
In Python, the __init__.py file is used to mark a directory as a Python package. It is used to initialize the package when it is imported. The __init__.py file can contain code that will be execute...
How do I sort a dictionary by key or value?
To sort a dictionary by key in Python, you can use the sorted function, like this: d = {"a": 1, "b": 2, "c": 3} sorted_d = sorted(d.items(), key=lambda x: x[0]) sorted_d will now be a list of tuple...
How do I list all files in a directory using Python?
To list all files in a directory in Python, you can use the os module and its listdir() function. This function returns a list of all the files and directories in the specified directory. Here's an...
How to Copy Files in Python?
To copy a file in Python, you can use the shutil module. Here is an example of how you can use the shutil.copy() function to copy a file: import shutil shutil.copy('/path/to/source/file', '/path/to...
Convert bytes to a string in Python and vice versa?
To convert a string to bytes in Python, you can use the bytes function. This function takes two arguments: the string to encode and the encoding to use. The default encoding is utf-8. Here is an ex...
What is the difference between str and repr in Python?
In Python, str is used to represent a string in a more readable format, while repr is used to represent a string in an unambiguous and official format. The main difference between the two is that s...
How to check if a string contains a substring in Python?
There are multiple ways to check if a string contains a specific substring. Using in keyword You can use in keyword to check if a string contains a specific substring. The expression will return bo...
How to catch multiple exceptions in one line (except block)?
To catch multiple exceptions in one except block, you can use the following syntax: except (SomeException, DifferentException) as e: pass # handle the exception or pass If you are using Pyt...
How do I get the current time in Python?
There are two ways you can get the current time in python. using the datetime object using the time module Using the datetime object First, you need to import the datetime module. Then by calling t...
How to iterate over Python dictionaries using 'for' loops?
Let’s assume the following dictionary: my_dictionary = { 'key1': 'value1', 'key2': 'value2', 'key3': 'value3' } There are three main ways you can iterate over the dictionary. Iterate ov...
Finding the Index of an Item in a Python List?
To find an index of the first occurrence of an element in a given list, you can use index method of List class with the element passed as an argument. The syntax is the following: my_list = [1,2,0,...
Understanding slicing in Python?
Slicing is a way of extracting a specific part of an array. The syntax is following: mylist[start:end] # items start through end-1 mylist[start:] # items start through the rest of the array ...
Difference between static and class methods in Python?
Class method To create a class method, use the @classmethod decorator. Class methods receive the class as an implicit first argument, just like an instance method receives the instance. The class m...
How to flatten a list in Python?
You can flatten a list in python using the following one-liner: flat_list = [item for sublist in l for item in sublist] In the example above, l is the list of lists that is to be flattened. The pre...
How to access the index in for loops in Python?
In python, if you are enumerating over a list using the for loop, you can access the index of the current value by using enumerate function. my_list = [1,2,3,4,5,6,7,8,9,10] for index, value in enu...
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