Python Coding challenge - Day 775| What is the output of the following Python Code?

 

Code Explanation:

1. Importing the asyncio Library

import asyncio

This imports the asyncio module — a built-in Python library used for writing asynchronous (non-blocking) code.

It allows multiple operations (like waiting, I/O, etc.) to run concurrently instead of one-by-one.

2. Defining an Asynchronous Function

async def double(x):

The async def keyword defines a coroutine function — a special kind of function that supports asynchronous operations.

Here, double(x) will take an argument x and run asynchronously when awaited.

3. Simulating a Delay

    await asyncio.sleep(0.05)

The await keyword pauses execution of this coroutine for 0.05 seconds without blocking other tasks.

During this pause, other async functions (like another double()) can run — that’s what makes it concurrent.

4. Returning the Computation Result

    return x * 2

After the 0.05-second delay, it returns twice the input value (x * 2).

For example, if x = 3, it returns 6.

5. Defining the Main Coroutine

async def main():

Another coroutine named main() — it will control the execution of the program.

This function will call multiple async tasks and gather their results.

6. Running Multiple Async Functions Concurrently

    res = await asyncio.gather(double(2), double(3))

asyncio.gather() runs multiple coroutines at the same time (here, double(2) and double(3)).

Both start together, each waits 0.05s, and then return results [4, 6].

The await ensures we wait until all of them are finished and then store their results in res.

7. Printing the Combined Result

    print(sum(res))

res is [4, 6].

sum(res) = 4 + 6 = 10.

So, the program prints:

10

8. Running the Event Loop

asyncio.run(main())

This starts the event loop, which executes the asynchronous tasks defined in main().

Once finished, the loop closes automatically.

Final Output:

10

500 Days Python Coding Challenges with Explanation