Both function compute the quotient and remainder(or modulo) for unsigned integers.

`unsigned_div_rem` takes `felt` arguments

`uint256_unsigned_div_rem` takes `Uint256` arguments.

Recall that Uint256 integers are encoded as two felts representing the 256 bits as two 128 bits numbers `low` and `high`.
```
struct Uint256 {
  low: felt   \\ 128 low bits
  high: felt  \\ 128 high bits 
}
```

Thus, `uint256_unsigned_div_rem` needs to do more thorough checks than the felt version to make sure the encoding is safe and sound.
Namely, it calls `uint256_check` on return values and needs to verify the result (gotten via a hint).
Those checks can be seen here in the [source](https://github.com/starkware-libs/cairo-lang/blob/master/src/starkware/cairo/common/uint256.cairo#L211), while the [felt counterpart is more straightforward](https://github.com/starkware-libs/cairo-lang/blob/master/src/starkware/cairo/common/math.cairo#L297). 

In general, functions using the Uint256 struct will be less efficient than their felt counterpart.

Additional resources can be found [here](https://github.com/milancermak/starknet-tokens-showdown) and [here](https://mirror.xyz/0x845605C411132BAA06024a521a85B653F3C802dF/wfUO8KSz2IAt8yg4oslsc1HDsJqMJ6HpQAukhjwZUUU).

Can someone explain the difference `between unsigned_div_rem` and `uint256_unsigned_div_rem`?

Why unit version process so many extra steps, but overall number of steps for computing are different for these methods?



Can someone explain the difference between unsigned_div_rem and uint256_unsigned_div_rem?

Your first option makes more sense.

Uint256 is a hack to implement 256 bits integers that are greater than the max felt.

It is also the option OpenZeppelin chose as shown in their ERC20 implementation of `decimals` ([here for uint8](https://github.com/OpenZeppelin/cairo-contracts/blob/c48025933679c3e5a2a1474a2967a4b6f2ca506c/src/openzeppelin/token/erc20/library.cairo#L65))

You only have to check the range using `assert_le` every time you set the value of the uint32 or create a special helper function for that.

Hey!
I had a question about what would be the cleanest way to imitate a `uint32` or `uint64` in cairo. Two approaches came to mind:
1. Simply use a felt and check that is less than `2**32 - 1`
2. Pass a Uint256 and check that var.high == 0 and var.low is less than `2 ** 32 -1`

First approach seems straightforward, but I wanted to know if there was a convention for this or a better way.

How to check for smaller Uints in Cairo?

Session keys have been theorized and discussed as a UX improving feature for Account wallets.
The Account Abstraction model surely allows session keys via wallet plugins theoretically. In practice, a few projects have produced PoCs (see briq or cartridge-gg) but no standard implementation exists as of yet.

More info can be found [here](
https://mirror.xyz/matchboxdao.eth/VXOvLKIvfXHP-cusKHw55zqlHpvvWwzh_fqm6j48Yek)

Does AA support "Session Keys" so I can avoid signing too many transactions when they are redundant?

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Does Account Abstraction support "Session Keys"?

The short answer is probably no.

StarkEx is not general purpose and currenty doesn't support executing Kakarot or any complex StarkNet contract, as is. 

See a [list of current StarkEx features](https://starkware.co/starkex/)

What is more probable is for Kakarot zkEVM to be implemented as a Layer 3 over StarkNet (e.g. using [slush](https://slush.dev/)).
This is worth discussing in the [Kakarot channels](https://www.kakarot.org/).


Can we deploy kakarot zkEVM on StarkEx and then run multiple solidity dapps on top of it?

Deploying kakarot evm on starkEx

Ahoy Caironauts,

  How can I define two functions with the same name but not the same arguments, e.g, 

- `func test()`
- `func test(param: Uint256)`

It is possible in Solidity and I'm trying to find the Cairo equivalent.

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