# Python Code Example: passing list to method

This code snippet defines a function that doubles each element in a list and then demonstrates its use by doubling the elements of a given list.

## Code Example

``````def doubles(l):
for i in range(0, len(l)):
l[i] = 2 * l[i]

myList = [12, 20, 14, 4, 5, 44, 74]

doubles(myList)

print("values from array doubled: ")
for i in range(0, len(myList)):
print(myList[i], end=' ')``````

### Output

``24 40 28 8 10 88 148``

### Code Explanation

#### Function `doubles(l)`

``````def doubles(l):
for i in range(0, len(l)):
l[i] = 2 * l[i]``````
• Purpose: This function modifies a list `l` by doubling each of its elements.
• Parameter: The function takes one parameter `l`, which is a list of numbers.
• For Loop:
• The loop iterates over each index `i` of the list from 0 to `len(l) - 1`.
• Inside the loop, each element at index `i` is multiplied by 2 and the result is assigned back to `l[i]`.
• Effect: The list `l` is modified in place, meaning the original list passed to the function will be changed.

#### Main Program

``myList = [12, 20, 14, 4, 5, 44, 74]``
• List Initialization: A list `myList` is created with the values `[12, 20, 14, 4, 5, 44, 74]`.
``doubles(myList)``
• Function Call: The `doubles` function is called with `myList` as its argument. This will modify `myList` by doubling each of its elements.
``print("values from array doubled: ")``
• Print Statement: This line prints a message indicating that the values from the array have been doubled.
``````for i in range(0, len(myList)):
print(myList[i], end=' ')``````
• For Loop and Print:
• This loop iterates over each index `i` of the list `myList` from 0 to `len(myList) - 1`.
• Inside the loop, each element of `myList` is printed on the same line separated by spaces. The `end=' '` argument in the `print` function prevents a newline from being added after each print statement, resulting in a single line output.

### Example Execution

When the main program is executed, the following steps occur:

1. The list `myList` is initialized with the values `[12, 20, 14, 4, 5, 44, 74]`.
2. The `doubles` function is called with `myList` as the argument, which modifies `myList` to `[24, 40, 28, 8, 10, 88, 148]`.
3. The modified list is printed with the message “values from array doubled: “.