`from starkware.starknet.compiler.compile import get_selector_from_name`


then use 


`get_selector_from_name('function_name')`


﻿  



ㅤ
_This answer was originally posted on [Triality](https://triality.org/question/627)_

How do I get the function selector or the hash from the function name in Cairo?


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/627)_

Cairo: Getting function selector

Hello! This is day 8 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 “Field Elements”.  Perhaps you can help me?

```
// Unlike most systems where the primitive type is a 32 or 64-bit integer,
// the primitive type in Cairo is "felt", which stands for "field element".
// When we say "a field element" we mean an integer in the range -P / 2 < x < P / 2,
// where P is a very large (prime) number.
// Currently we use a 252-bit number (76 decimal digits).
// When we add, subtract or multiply and the result is outside the range above,
// there is an overflow.
//
// The most important difference between integers and field elements is division:
// Division of field elements (and therefore division in Cairo) is not the
// integer division you may be used to.
// In the next challenge, you'll see how to use unsigned_div_rem()
// for truncated (i.e., rounding down) integer division.
//
// Make the code below output the results of the following expressions:
// 1. 1 + 100, 1 - 100, 9 * 9.
// 2. pow(10, 74), pow(10, 75), pow(10, 76)
// 3. 12 / 3, (-12) / 3
// 4. 13 / 3 (This is an example of division in the field)

%builtins output

from starkware.cairo.common.serialize import serialize_word

// Computes base^exp.
func pow(base: felt, exp: felt) -> (res: felt) {
    if (exp == 0) {
        return (res=1);
    }

    let (res) = pow(base=base, exp=exp - 1);
    return (res=res * base);
}

func main{output_ptr: felt*}() {
    serialize_word(1 + 100);
    // Add your code here.

    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)*

How to make math operation with Field Elements (felts) in Cairo lang?

Hi all,

Am planning on starting a mainnet node and running it in a docker container as per these instructions:
https://github.com/eqlabs/pathfinder/#running-with-docker

My question:
I am already running a full Ethereum node on my server. I this case, can I set the  PATHFINDER_ETHEREUM_API_URL parameter to my node's endpoint, i.e. 127.0.0.1:[eth node rpc port]?

Thx.

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

I am already running a full Ethereum node on my server. Can I set the  PATHFINDER_ETHEREUM_API_URL parameter to my node's endpoint for pathfinder?

Is there a way/a tool that can automatically generate events for Cairo functions, since pretty much all of my events follow the same format


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/221)_

Cairo Automatic Events

Starknet is using which oracle service provider?

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

Which oracle service provider is StarkNet using?

Hey! I have a contract deployed on Testnet. Let's say its address is `0x1234`.

I want to get its ABI somehow, but I don't have the code of the contract, because it wasn't deployed by me.

I'm using StarkNet.py to interact with StarkNet.

Does anyone know the answer?

How to get the contract ABI using Starknet.Py?

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, I am trying to implement the connect wallet : ``` import { useConnectors } from '-react/core' function YourComponent() { const { connect, connectors } = useConnectors() return ( <div> {connectors.map((connector) => connector.available() ? ( <button key={connector.id()} onClick={() => connect(connector)}> Connect {connector.name()} </button> ) : null )} </div> ) } ``` I feel like connectors will only give the wallet if I have it on my chrome extensions , so whats the point of connector.available() ? I am using : ``` const connectors = getInstalledInjectedConnectors() ```

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

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