How to determine type when using a library.

[Olaleye-Blessing]

Thanks for this wonderful video, @PatrickAlphaC.
I'm on lesson 4.

In the PriceConverter library, I noticed all the functions and arguments are uint256. So I guessed that's why using PriceConverter for uint256 was used in FundMe contract.

When I checked solidity by example, two different types are used in the function library. And using Balances for * was used while using the library in Token Contract.

My question now is how do I know which type to use? And Instead of specifying * for any data type, is there a way to specify that I only want to use uint and string for a library?

[alymurtazamemon]

@Olaleye-Blessing

If you have all functions inside the library that return the same data type, then in the parent contract you will only use

using LibraryName for data_type;

But if you have multiple functions with the different return types, then you use them separately for each data type you want in the parent contract. like this

using LibraryName for uint256; //example
using LibraryName for string; // example

hope it clears you answer.

[PatrickAlphaC]

Nice one!