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my attempt is to call a view function to reatrieve some data from a contract on the Blockchain using a C program. I do have the interface of the contract.

I think i need to performe two things in order to accomplish this task:

  • First of all the program needs to connect to a node running the EVM. Usually easy using Metamask and web3.js. I don't thinks it's so easy even in this case. Is it possibile to connect to a node without using Metamask? What would you do to do this? What do you think will be the biggest problem of this task?
  • Second i need to create a raw transaction to send to the node and by raw i mean real raw. Anyway once i've a connection this shouldn't be impossible. Since i just need to call one function i was thinking of making one call using remix or truffle then inspect the data sent and try to replicate it the connection opened from the C program. Do you think it's possible to do such a thing? What part does it seems impossibile to you?

Of course i also ask you if you know of any project or any people who have done something like this, even in other languages, i'll really appreciate if you post it.

D.Rek
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  • I am developing a wallet , entirely in C++ , it sends transactions to contracts and EOAs , so , it is possible to do what you want in C. But I wonder why would you need C if you are more like a Java programmer. – Nulik Aug 21 '18 at 19:28
  • @Nulik thanks for your reply. The device who should then run the program isn't mine, they told it can't run the JVM and it must be done in C. – D.Rek Aug 22 '18 at 06:42
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    well, the shared library with all the functions to send transactions is 4.1M , add the code to actually use the library + send raw transaction to the network via HTTP and that's what you will have as executable size at the end. And my wallet is 14MB including debugging symbols, unstripped, unoptimized. – Nulik Aug 22 '18 at 13:12

2 Answers2

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Is there a c++ library to encode abi

you need to change stream operations to char * stuff.
info on how to encode args https://docs.soliditylang.org/en/v0.5.3/abi-spec.html
so you need a node provider and some service to sign tx without having key in code. i use ethsigner

Алексей Неудачин
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I think you can refer to native dapp. We can binding golang code to smart contract then call it

https://github.com/ethereum/go-ethereum/wiki/Native-DApps:-Go-bindings-to-Ethereum-contracts

Tony Dang
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  • I'll take a look to it as soon as i can and then i'll let you know. Thanks for your fast reply. – D.Rek Aug 22 '18 at 06:46
  • okay, you can refer to c-like lib also: https://nethereum.readthedocs.io/en/latest/#what-is-nethereum – Tony Dang Aug 22 '18 at 11:05