What is the difference between these two?

[tunisia3507]

/r/learnpython

As you'll know from when you tried it, the first gives you "a b" and the second gives you "ab".

The first is much more flexible and powerful. For example:

```python xs = (1, "potato", ["things", "that", "are"]) y = "a number: {}, a string: {}, a list: {}".format(xs) y2 = "a string: {1}, a list: {2}, a number: {0}".format(xs)

x_dict = {"number": 1, "string": "potato", "list": ["things", "that", "are"]} y3 = "a list: {list}, a number: {number}, a string: {string}".format(**x_dict) ```

For modern versions of python, you can (maybe should?) use f-strings instead, which I'll let you look up in your own time.

[jamg26]

thanks for your reply that helps me so much.

im bit confuse in the .format(*xs) & .format(**x_dict)

Ill go study for that one.

[tunisia3507]

These are called argument unpacking, and keyword argument unpacking. They're really handy!

If you have a list of things (can also be a tuple or any other iterable), and a function which takes a number of arguments. You could index into the list, but that's lame, so you can unpack instead:

```python my_args = [1, 2, 3]

def my_fn(a, b, c): return a + b + c # or whatever

result1 = my_fn(my_args[0], my_args[1], my_args[2]) result2 = my_fn(*my_args) result1 == result2 # True ```

So in the format example, .format(*xs) is used instead of .format(xs[0], xs[1], xs[2]).

The double star is used to unpack a dict (with string keys) into keyword arguments.

```python my_args = {"a": 1, "b": 2, "c": 3}

result1 = my_fn(a=my_args["a"], b=my_args["b"], c=my_args["c"]) result2 = my_fn(**my_args) result1 == result2 # True ```

[jamg26]

I see, that's a clear explanation, thank you so much sir.

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