sry,ser,just checked your l2 tx status shows **accepted on l2**,pls wait until it shows **accepted on l1**,(Usually you need to wait 10+ hours),then pls reopen the starkgate page to check if there have a secondary confirmation dialog box popped up, click to complete transfer and the funds will arrive in your mm wallet,for details pls check：https://discord.com/channels/793094838509764618/957558236662366219/978172477777797171 ,thank you🤝

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

Newton

I transferred USDC from Starknet to L1 via Starkgate.
In Starknet Explorer, it shows the assets received on L1, but I have no USDC received on L1. It’s been more than 12 hours. What could be the problem?!

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

Problem with transfering USDC via Starkgate. Can anyone help?

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?

What libraries are secure to use in the Cairo language? How to know which library is audited? 

What libraries are secure to use in Cairo?

Just saw this in Cairo v0.10 docs: "support using functions as expressions"
Can anyone explain how does that work exactly? any example would be very helpful
It's mentioned here: https://github.com/starkware-libs/cairo-lang/releases/tag/v0.10.0#:~:text=Support%20using%20functions%20as%20expressions

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

Can you explain Cairo v0.10 usage functions as expressions?

Hey this message looks very confusing.
`GatewayError: {'contract_address': ['Expected hex string, got: "0x01C438231cD70f47d1acB8404E51734c1Fb4d79AC55813b3E861fB1EF78Da0D6".']}`

Any hints on this?

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

CairoLang error: `GatewayError: {'contract_address': ['Expected hex string, got: 

How to convert tokens on starknet? Any DEXs AMMs?

Something that isn't on testnet.

Am going through all these projects on the ecosystem page but am coming up with nothing.

Would be nice if there was a DEX/AMM section ... instead of making people go through all those projects one by one to see what they actually do.

I'm up to Magnety ...

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

How to convert tokens on starknet? Any DEXs AMMs?


Hello everyone. Does anyone happen to know if there's a way to get the block hash in cario? I found out about `get_block_number` and `get_block_timestamp`, but is there something similar for block hash?

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

How to get the block hash in Cairo lang?

Hey guys, has anyone had `get_caller_address` problems in devnet ? I feel like it's returning address 0 when it shouldn't so I made this small contract to test it

```%lang starknet

from starkware.cairo.common.cairo_builtins import HashBuiltin

from starkware.starknet.common.syscalls import (get_caller_address)


func caller_addr() -> (res: felt) {
}



func fn_to_be_called{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr: felt}() {
    let (caller) = get_caller_address();
    caller_addr.write(caller);    

    return ();
}


func get_caller_addr{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr: felt}() -> (caller_addr: felt) {
    let (caller) = caller_addr.read();

    return (caller_addr=caller);
}```

and indeed `get_caller_addr` return address 0 after I called `fn_to_be_called` in the devnet. This is causing some problems in more complex contracts of course. Is it just me ?



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

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