You can solve it one of the following two ways:


1) declare main like this


`main{syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, range_check_ptr}()`


2) add a with statement inside your function:


 `with range_check_ptr:`


 `let (result) = uint256_signed_lt(zero, one)`


 `end`


The first one is the most logical answer as it is less management and less code to resolve and can be reused in any other functions that need implicit range_check_ptr


ㅤ
_This answer was originally posted on [Triality](https://triality.org/question/308)_

How can I resolve this issue?


I'm trying to prove that the left uint is smaller than the right uint using this function:


`func main(syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, range_check_ptr):`


 `let zero = Uint256(0, 0)`


 `let one = Uint256(1, 0)`


 `let (result) = uint256_signed_lt(zero, one)`


`end`


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/308)_

Cairo Error: 'range_check_ptr' cannot be used as an implicit return value. Consider using a 'with' statement.

Hello! This is day 15 of the 17 days of the Cairo Challenge. And I have no idea how to solve the [playground](https://www.cairo-lang.org/playground/) exercise “SHARP”.  Perhaps you can help me?

```
// The program below lets you choose a number `x` and output its square `y = x*x`
// (proving that you know the square root of `y`).
//
// 1. Replace "YOUR_NUMBER" with a value of your choice, run the program and
//    make sure you get the expected output (the square of the value you chose).
//
// Take a look at the output line saying "Program hash: ...".
// The program hash is the (Pedersen) hash of the compiled program.
//
// 2. The compiled program does not include the [hints](https://cairo-lang.org/docs/how_cairo_works/hints.html),
//    so changing any code within a hint does not change the resulting program
//    hash.
//    Try changing `x` to a different number and note that the program hash remains
//    unchanged after rerunning.
//
// The Cairo SHARP collects several programs and creates a proof that they ran
// successfully. Such a batch of programs is called a "train".
// Note that it may take a while until a train is created, as the service waits
// to collect enough programs (after a certain amount of time, the train will
// be dispatched, even if it's not full).
//
// 3. Click on "Prove with SHARP" to prove the program using the shared proving service.
//
// After the proof is created, SHARP sends it to an [Ethereum goerli contract](https://goerli.etherscan.io/address/0xAB43bA48c9edF4C2C4bB01237348D1D7B28ef168).
// For each job in the train, a corresponding fact is registered on the contract,
// attesting to the validity of the run with its particular output.
//
// 4. You can monitor the status of your job, using the link in the output pane.
//
// For each job, the corresponding fact is computed as follows:
//   keccak(program_hash, keccak(program_output))
// where:
// * program_hash is the hash of the compiled program, which you can find in
//   the output pane (32 bytes).
// * program_output is the output of the program as a list of 32-byte
//   elements.
//
// For example, if you chose x=3, the output will be [9] and you can compute
// the fact in Python using:
//
//   from web3 import Web3
//
//   program_hash = 0x114952172aed91e59f870a314e75de0a437ff550e4618068cec2d832e48b0c7
//   program_output = [9]
//   Web3.solidityKeccak(['uint256', 'bytes32'], [
//     program_hash,
//     Web3.solidityKeccak(['uint256[]'], [program_output])
//   ])
//
// You can also find your job's fact in the SHARP tracking page you opened
// in step 4.
//
// 5. Once you see that the fact is registered, you can call the
//    [contract's isValid() method](https://goerli.etherscan.io/address/0xAB43bA48c9edF4C2C4bB01237348D1D7B28ef168#readContract) to make sure it's indeed registered.

%builtins output

from starkware.cairo.common.serialize import serialize_word

func main{output_ptr: felt*}() {
    alloc_locals;
    local x;
    %{ ids.x = YOUR_NUMBER %}

    serialize_word(x * x);
    return ();
}
```

---

> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

What is SHARP in Cairo Language?

Can anyone share some articles explaining SNARK/STARK concepts and rollups (Optimism)?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Can anyone share some articles explaining SNARK/STARK concepts and rollups (Optimism)?

Does anyone know how to print a uint256 in protostar tests?

```
let (local balance) = IERC20.balanceOf(asset, owner);
%{
    balance = reflect.balance.get()
    print("current owner balance: ", balance)
%}
```

this errors out: [https://github.com/software-mansion/protostar/issues/1129](https://github.com/software-mansion/protostar/issues/1129)

Does anyone know how to print a uint256 in protostar tests?

I have a question about how to print "Hello World" in Cairo 1. How do I log/print ?

How do I log/print in Cairo 1.0?

Hey, is there a unsigned_div_rem supporting dividing by 2**128 ?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Is there a unsigned_div_rem supporting dividing by 2**128 ?


Hello! This is day 16 of the 17 days of the Cairo Challenge. In this exercise it is required to submit your first StarkNet contract. When you try to make it, you get an error:

```solidity
Error: code:20:1: Unsupported %lang directive. Are you using the correct compiler?
%lang starknet
^************^
```

Can you show your solution to [playground](https://www.cairo-lang.org/playground/) exercise “StarkNet contract” and also send a link to your contract, and a screenshot where you use your `add` method?

```solidity
// [StarkNet](https://starkware.co/product/starknet/) is a permissionless decentralized ZK-Rollup operating
// as an L2 network over Ethereum, where any dApp can achieve
// unlimited scale for its computation, without compromising
// Ethereum's composability and security.
//
// This is a simple StarkNet contract.
// Note that you won't be able to use the playground to compile and run it,
// but you can deploy it on the [StarkNet Planets Alpha network](https://medium.com/starkware/starknet-planets-alpha-on-ropsten-e7494929cb95)!
//
// 1. Click on "Deploy" to deploy the contract.
//    For more information on how to write Cairo contracts see the
//    ["Hello StarkNet" tutorial](https://cairo-lang.org/docs/hello_starknet).
// 2. Click on the contract address in the output pane to open
//    [Voyager](https://goerli.voyager.online/) - the StarkNet block explorer.
// 3. Wait for the page to load the information
//    (it may take a few minutes until a block is created).
// 4. In the "STATE" tab, you can call the "add()" transaction.

// The "%lang" directive declares this code as a StarkNet contract.
%lang starknet

@view
func add(x: felt, y: felt) -> (res: felt) {
    return (res=x + y);
}
```

---

> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

How to submit a StarkNet contract?

Does AA work on Mobile?

---

This question is participating in [Newton Bounties | Incentivized Test Program](https://www.notion.so/Newton-Bounties-Incentivized-Test-Program-94322ad48e7d40a3adcf36f6b26174cd) Every verified valid question gets $10 USDC (mainnet)

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Cairo Error: 'range_check_ptr' cannot be used as an implicit return value. Consider using a 'with' statement.

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