output_ptr Assertion Error in Main - Cairo-lang

Why does this Cairo program put powers of 2 in the memory?

What does it mean to declare a 'local' variable inside a 'let'?

Checking result of an L1 -> L2 message/invoke in Starknet

when to use tail call optimization in a cairo smartcontract

What is the inefficiency in this cairo code using alloc_locals

Why does range_check_ptr chek for [0, 2^128) instead of [0, P/2)

Testing Starknet Cairo contract function with address

How to generate a proof for a Cairo program and verify it?

Where can I find a list of decorators available in Cairo?

How to disable error squiggles for Cairo Compiler in VS Code

How do I develop against cairo devnet with browser wallets?

Does Cairo support int256, or negative numbers in general? 

How can i learn Cairo with Python base?

Cairo: How to reassign Uint256 in a conditional

Cairo: Difference between amount and gas_fee

Cairo Error: 'While expanding the reference 'test_struct' in'

Changing a variable with an initialized value recursively with if statements

How expensive are bitwise operations (and/or/xor) vs arithmetic in Cairo?

How to calculate the sum of the digits of a felt in Cairo?

Cairo: How do I write a custom error message when an assert fails?

Cairo Error: Getting Expected expression of type 'felt', got '__main__.getCurrNumber.Return'

Cairo error for Unexpected '.' after ... which is future

Cairo Error: Getting Expected expression of type 'felt', got '(res : felt)'

Did not have to pay gas fee when calling same function multiple times in Starknet?

Cairo: Javascript API for cairo compile

How many Cairo steps does it take to compute one Pedersen hash?

Cairo: How would I store negative numbers then retrieve them as negatives?

How to write "and" conditional logic in Cairo?

How do I write a log based 2 function in Cairo?

Cairo error: Accessing struct/tuple members for r-value structs is not supported yet

Cairo error: Unknown identifier 'bitwise_ptr' when using keccak

Cairo 0.10.0 Error: Cannot unpack return value error

Cairo: How to return true from a function?

How large can addresses be in Cairo?

Cairo: Getting function selector

Cairo: How do I iterate through an array of structs?

Cairo: Unknown value for memory cell at address

Cairo: Getting the zero address

Cairo: Expected '__main__.Id' to be a struct. Found: 'future'

Cairo Error: Unexpected token Token('LPAR', '('). Expected: identifier.

Writing a "not" operation in Cairo

Cairo: Iterating through arrays

How do you check if a number is even in Cairo?

Cairo Error calling function: Expected 'function_name' to be a struct. Found: 'function'.

Namespaces in Cairo

Cairo: How do I find the current contract's address?

Declaring Strings in Cairo

Implicit Arguments in Cairo

Does cairo have payable functions?

What does ret do in Cairo?

Cairo: When do you use tempvar and when do you use local

Getting the CLASS_HASH of a contract in Cairo

Cairo: How do write a log function in Cairo

Cairo: Using less than or greater than in conditional

Cairo: Cannot unpack multiplication error

开始学习Cairo

Cairo: What is the difference between let and tempvar?

Expect function call to fail in cairo?

Cairo: are builtins always needed to be expressed in function signature?

Cairo: Cannot unpack error

Cairo: Else if statement

Cairo: How do I initialize an array in cairo

Cairo: Getting the squared summation of felts in an array

Cairo error "Expected expression of type 'starkware.cairo.common.uint256.Uint256' to have an address."

Immutable Memory in Cairo

Cairo start.

How to import uint256 in Cairo?

Cairo Passing Functions

Cairo v. Solidity

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

Cairo Array Item Removal

Searching for Cairo Questions

Cairo Automatic Events

Cairo Owner Only Fuctions

Infinite Recursion Error on Cairo Compile

Cairo Multiple Storage Vars

test another new question new

Creating Elements via a function

List of Cairo Decorators

Cairo: Where/how is it defined and why is it much smaller than the field prime?

How to calculate the minimum decimal number that can store 20 chars long string as a field element?

How to fix `bud_ptr`

hardhat test

Any idea what this could be caused by?

signing a message using account.signMessage(data) | starknet.js

Another vanilla Cairo question, what are the sorts of references

Hey, is there anyway to debug Cairo contracts in hardhat environment? Something like hardhat console in solidity

a pointer with a hint, without doing a memory allocation

Is it possible to import local python files into hints?

Does writing it to zero actually do something?

Which is this extension that shows you errors before compilation ser?

 Is there a way to accelerate pytest for cairo contract?

A plan to get better visibility when a transaction got received but not placed into a block?

Abi.encode and Abi.decode in Cairo?

Cairo OR operator

Cairo: let vs tempvar what is the difference?

anyone know how to disconnect the connected wallet on the frontend with starknetjs or another way?

Does anyone know a vim plugin for StarkNet smart contracts?

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?



vargastartup

Can someone explain the difference between unsigned_div_rem and uint256_unsigned_div_rem?

Hey, I’m learning Cairo and I want to know more about Gas Optimization. In Solidity compiler, there is a difference between writing uint128 and uint256. Similarly to C and other languages, for example:

```solidity
contract ThisIsNotAnOptimizedContract{
	uint128 Zero;
	uint256 One;
	uint128 Two;
}

contract ThisIsAGasOptimizedContract{
	uint128 Zero;
	uint128 Two;
	uint256 One;
}

```

`uint128` variables each occupy a separate `uint256`just for themselves, wasting 128 bits for each slot (Like the first contract). The Solidity compiler puts 2 `uint128` in the one 256-bit memory slot when they are declared next to each other. 

I’m curious if there is any similar issue in Cairo. `Uint256` uses two felt objects for low/high bits of the value.

```python
struct Uint256 {
    // The low 128 bits of the value.
    low: felt,
    // The high 128 bits of the value.
    high: felt,
}
```

Is there any similar practice in Cairo to optimize `felt` and Uint256 objects to save some compiler steps?

How do you optimize gas in Cairo with Uint256/felt?

when i am planing to send a token ,it always goes wrong

how to send token 

Can someone explain to me what Implicit arguments are? How do they work in Cairo lang?

Newton

What Implicit arguments are in Cairo lang?

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?

1. Can anyone explain how to get Goerli ETH tokens?

2. Also want to know how to bridge tokens from the Goerli ETH testnet and move them to Goerli2 (StarkNet)?


---

> thank's for your answers, summing up how to transfer funds and how to use Faucet on Ethereum:


1. For receiving ETH on Goerli Test Net, I used [Goerli PoW Faucet](https://goerli-faucet.pk910.de/).
As an alternative, [https://goerlifaucet.com/](https://goerlifaucet.com/) can be used, but it is required to authorize.

2. I installed ArgentX using the links below and transferred funds using the [HashStack service for StarkNet](https://goerli2-bridge.hashstack.finance)

![https://www.bbntimes.com/images/Ethereum_Faucet.jpeg](https://www.bbntimes.com/images/Ethereum_Faucet.jpeg)

StarkNet Faucet: How can I get a Goerli-2 eth faucet tokens (StarkNet)?

Is there any blockchain project contract supporting web2 scripts executable on VIa EVM?

I think it only one Tru (truebit)

Is there any blockchain project contract supporting web2 scripts executable on VIa EVM?

1. What’s the difference between AA (Abstract Account) and EOA (Externally Owned Account)?

2. What is an abstract account? Where is the account address derived from? Does the account address also come from the mnemonic and the private key?

3. What is multi-call? What will it bring to UX?

Can you explain what is Abstract Account?

Looking to call the approve and transfer functions for an erc-20 in the same transaction. Thoughts on how to do this?


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/1218)_

Cairo: How can i approve erc20 and transfer in the same transaction?

There are many people who are pretty new to Cairo Language, so this thread is about some good resources, to begin with. What projects, educational courses, Github Repos etc. about StarkNet can you recommend?

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What resources (Github repos, projects) do you follow about Cairo Language? Why?

What will the bundler ecosystem look like in AA?

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What will the bundler ecosystem look like in Account Abstraction?

What is an abstract account? Where is the account address derived from? Does the account address also come from the mnemonic and private key?

What is an abstract account? For example: StarkNet Account Abstraction

Does AA support bundling multiple operations at once?
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Does Account Abstraction (StarkNet) support bundling multiple operations at once?

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"?

There are a bunch of questions about key storage in a new "Account Abstraction" paradigm.
1. Can I recover my key if I lose it?
2. Can I have a key-less wallet?
3. Can I easily create new wallets like in Metamask "Add Account" with only 1 seed phrase?
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How will work an account abstaction wallet with the key?

Does AA support "Burner Accounts" so I can connect a new account to a new dApp without worrying about losing all my funds?

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Does Account Abstraction support "Burner Accounts"?

How does Account Abstraction improve the UX compared to other methods?

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How does Account Abstraction improve the UX compared to other methods?

What’s the difference between Account Abstraction (AA) and Externally Owned Accounts (EOA)?

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What’s the difference between Account Abstraction (AA) and Externally Owned Accounts (EOA)?

Does AA work on Mobile?

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Does Account Abstraction work on Mobile?

What are multi-calls in Account Abstraction? What will it bring to the UX?

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