Lesson 2: Array are not clear

[Salutix]

Hello!
In video Patrick said, that in [ ] brackets we put the quantity of items in array. But when creating addPerson function we created a mapping and after it wrote: "nameToFavoriteNumber [_name] = favoriteNumber".
As I understand it now, in this case [_name] doesn't define seize of array: it acts like a link to group of items of the same category (names in our case) and program understands, that it has to find specific item (name) in this group and then show number, connected with it.
Is this right? And maybe arrays have more functions than just these two?

Please try to explain as simple as possible :-) Just the beginner
Many thanks in advance!

[alymurtazamemon]

@Salutix Hey! These both are different things but because the symbol is the same that is why it is confusing you. Let me clear it up!

uint256 arrayName[3];

Here this [ ] symbol we use to create a fixed-size array. It indicates the length of the items it can contain.

nameToFavoriteNumber[_name] = _favoriteNumber;

But here [ ] this symbol has a different meaning, nameToFavoriteNumber is a mapping. The mapping you can think of it as a key/value pair (key => value). And it does not link 1 key with multiple values, it only links 1 key with 1 value.

So here what we are doing is that every time we call the addPerson function and pass name and favoriteNumber, It will do two 2 things, 1. It will create a new Person object with a given name and number and store it inside the Person array. 2. It will create a new member inside the mapping of a given key/value.

[Salutix]

Thank you for prompt answer, Ali!
Let me ask you clarifying question to make sure I got it right: [ ] not only represent arrays, but can have different meanings (e.g. as with mapping) depending on situation?
If the answer is YES, then how many meanings (approxomately)? Just wondering :-)

[alymurtazamemon]

@Salutix For now you just focus on these 2, if you see any other just create a new discussion and tag me I will clear it out.

[Salutix]

Got it, thank you for help!