In Python, integers are immutable, meaning that once created, their value cannot be changed. This raises the question of how to pass an integer by reference, allowing modifications made within a function to be reflected in the original variable.
Passing a Mutable Container
While it's not possible to pass an integer by reference directly, you can pass it in a mutable container, such as a list:
def change(x): x[0] = 3 x = [1] change(x) print(x)
Output:
[3]
In this example, we create a list x containing a single element. We then pass x to the change function, which modifies the value at index 0. Since lists are mutable, this change persists even after the function returns.
Returning a New Object
Another option is to return a new object with the modified value from the function:
def multiply_by_2(x): return 2 * x x = 1 x = multiply_by_2(x)
In this case, the multiply_by_2 function returns a new object with the doubled value, which is then assigned to x. The original integer x remains unchanged.
Best Practices
When passing integers to functions, consider the following best practices:
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