Questions tagged [c++]

All questions related to the use of C++ within the EOSIO framework

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Is it possible to set up a smart contract with multiple .cpp and .hpp files?

If we want to make our smart contract code modular, and keep each class, contract, and table in its own file, is it possible to do this, and if so, how?
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1answer
25 views

RPC Wallet integration API throwing an error

I am new with blockchain services. I have created wallet using command line. curl -X POST http://127.0.0.1:8888/v1/wallet/create -d '"WalletTest" It's created successfully. But, I'm trying to ...
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1answer
17 views

what are supported STL types in tables?

What are the supported STL types in tables? I'm specifically curious about std::pair
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1answer
20 views

template function in contract code with a lambda

This is more a C++ question than EOS contracts question but I am having trouble creating a template function for migrating tables to a different scope. I cannot get this to compile. template <...
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1answer
54 views

Transfer tokens inside a smart contract from an account to another account

I need to write a simple function that would send tokens using a different account action. Exactly the same situation as in these questions: one and two But I have to use not eosio.token contract but ...
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1answer
19 views

Defining symbols for a contract at compile time - how?

supposing I have a contract declaration in file t.cpp as follows: class [[eosio::contract("__CONTRACT__")]] token : public contract { I would expect to be able to compile it like this: $ eosio-cpp -...
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0answers
15 views

Can I deploy a contract from within a contract? [duplicate]

We can create accounts from contract code: https://github.com/angelol/smart_account_creator and we can query things about accounts: https://github.com/nsjames/Account-Has-Code is there a way to ...
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1answer
30 views

Contract won't keep index count inside index table

Attempting to keep track of an index for future use as an index in another container. uint64_t namehash = ::eosio::string_to_uint64_t(my_name.c_str()); auto name_iter = ...
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1answer
55 views

Passing the action name having return type to EOSIO_DISPATCH in EOSIO smart contract

I have following EOSIO smart contract: #include <eosiolib/eosio.hpp> #include <eosiolib/print.hpp> using namespace eosio; class random : public contract { public: using contract::...
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1answer
72 views

Does permission_level (_self) means that only contract can use this method?

If yes, then how do I make sure that anyone or any specified address can call a method? If not then what is the usage of permission_level (_self ...)? action{ permission_level{_self, "active"_n}...
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1answer
92 views

EOSIO: name.value secondary index returns end iterator, even though searched value exists in table

I've got a multi-index table going with two secondary indices: TABLE entry { uint64_t id = 0; eosio::name player; std::vector<uint16_t> allocation; ...
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1answer
98 views

How can I create a table in an .hpp for a general contract? (Using the CDT)

THE STRUCTURE OF MY PROJECT I am working in mycontract.cpp, which imports myheader.hpp WHAT I WANT I want to create a table in myheader.hpp, for a generic contract, "IN THEORY" as follows: struct [...
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1answer
111 views

Using transfer to send tokens within a smart contract results in “unable to find key”

This is my example code deployed on myaccount #include <eosiolib/eosio.hpp> #include <eosiolib/print.hpp> #include <eosiolib/currency.hpp> using namespace eosio; class ...
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1answer
117 views

Runtime Error Processing WASM in ``` std::stof```?

[[eosio::action]] void hi(){ string strNum; strNum.push_back('3'); float currNum = std::stof(strNum);// print("currNum=",currNum); } ...
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1answer
221 views

How to solve !action_type.empty(): Unknown action hi in contract hello?

I am following this doc: https://developers.eos.io/eosio-home/docs/your-first-contract. This is the hello.cpp contract code which is successfully deployed: #include <eosiolib/eosio.hpp> #...
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0answers
71 views

How to solve !action_type.empty(): Unknown action hi in contract hello?

I am following this doc: https://developers.eos.io/eosio-home/docs/your-first-contract. This is the hello.cpp contract code which is successfully deployed: #include <eosiolib/eosio.hpp> #...
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1answer
43 views

EOS CDT: where are the *.h and the *.cpp files stored in the filesystem, I need reference to them to compile

I'm trying to use the EOS CDT (contract development toolkit). I've downloaded and installed the repository from github, and used to following commands, as indicated from the eos.io development page. ...
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2answers
287 views

How to solve fatal error: 'eosiolib/types.hpp' file not found #include <eosiolib/types.hpp>?

After installing eosio.cdt 1.4.1, I am receiving this error from the compilation of my code where is included the header file eosiolib/types.hpp: fatal error: 'eosiolib/types.hpp' file not found ...
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1answer
101 views

How can i solve the error: iostreams currently clash with eosio::datastream?

I am trying to compile some code which compiled successfully with the old compiler eosiocpp, but with the new eosio-cpp gives me: eosio.cdt/1.4.0/bin/../include/libcxx/iostream:13:2: error: "iostreams ...
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2answers
100 views

Can I use uint256_t in EOS smart contracts?

I want to use uint256_t in my EOS smart contract but I am getting following error unknown type name 'uint256_t'; did you mean 'uint16_t'? I thought EOS supports uint256_t as I read it in some EOS ...
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2answers
131 views

Error 3015004 when creating tokens in tutorial

Caseys-MBP:eosio.token casey$ cleos push action eosio.token create '[ "eosio", "1000000000.0000 SYS"]' -p eosio.token@active Error 3015004: The type defined in the ABI is invalid Error Details: ...
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1answer
141 views

eosio.cdt 1.3.2 indexed_by error: non-type template argument is not a constant expression

I'm trying to shift my contract and build it with the latest CDT, v1.3.2. The transition docs say to use the new ""_n name constructor but it doesn't appear to be working. I have: typedef ...
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2answers
73 views

How to handle exceptions in the smart contract?

Let's say I need to send some EOS to 2 different addresses from within a smart contract! Now, let's suppose that one of those addresses is actually a smart contract and can reject the transfer! In ...
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1answer
154 views

Why smart contract function fails with “Error 3090004: Missing required authority”?

WHAT I WANT From the contract mycontract I want to call a function function1. The function function1 calls another function of mycontract called function2. The function function2 calls an action of ...
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1answer
285 views

Whats the use of EOSLIB_SERIALIZE?

I understand that it is used for serialization and deserialization of a struct but why does anybody want to serialize/deserialize the struct? What's the use case?
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1answer
45 views

How do I use C++11 on Mac?

I tried the hello world sample contract, and when it came time to compile, I got this error: hello.cpp:10:10: error: expected ']' [[eosio:action]] ^ ...
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1answer
359 views

How to pass a list / array / vector to an action? [duplicate]

I need to pass a list of integers to an action. It would be fine to use vectors or arrays, but I can't find one that works. Using vector in the smart contract compiles fine, but then I get this error ...
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1answer
351 views

Assertion failure after updating a smart contract with tables

Before the update Before the update of the code of my c++ smart contract, this uses to work absolutely fine. Data storing on the table and actions execution were done successfully. After the update ...
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1answer
83 views

Smart contract error while calling recover_key

Specs I am using the function recover_key from the library crypto.h at the following link: https://github.com/EOSIO/eos/blob/master/contracts/eosiolib/crypto.h Code int compressed_size = ...
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1answer
80 views

How to parse iso8601 to eos time format?

How does one parse an iso8601 string to eos time_point format?
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2answers
886 views

Transfer EOS tokens inside a smart contract from an account to another

I want to implement, in my smart contract(C++), a function that forwards EOS token to another account. This is actually a basic question, but is that possible actually? Please, could you share the ...
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1answer
73 views

Time dependent EOS unit test

My contract has time dependent actions, which I want to test. How can I mock the clock in the smart contract such that I can set it to any time I want? An example of one action that is time ...
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2answers
108 views

Do all Smart Contracts use the eosio namespace?

I'm new to creating Smart Contracts on EOS and I've followed a few tutorials (for example the official Hello World guide). Would someone be able explain why all of the examples seem to use the ...
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2answers
78 views

How to use std::tuple with eosiocpp?

I am trying to use typedef std::tuple<double, double> location_t; to create a simple tuple with latitude and longitude, but eosiocpp gives me 2018-09-02T12:54:47.310 thread-0 main.cpp:105 ...
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0answers
159 views

What are the main differences betwen EOSIO multi_index and Boost multi_index?

Inspired by this comment, I was wondering what are the main differences between eosio::multi_index and boost:multi_index and why do they exist? The documentation notes that there are important ...
3
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1answer
812 views

What's the difference between “time” and “time_point_sec”?

Seems that they are both datatype for storing number of seconds that have elapsed since 1970. So what's the difference between them, when should I use which? Edit: An example of the "time" datatype I'...
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2answers
924 views

How to convert asset to string in a contract?

How to convert asset to string in a contract? asset my_asset = asset(10000, S(4, EOS)); string my_asset_string = ??? //How to convert my_asset to a string "1.0000 EOS"?
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1answer
117 views

Is it possible to compile a smart contract using g++ or clang?

I want to write and execute some unit tests on a smart contract outside of nodeos, but to do that I need to be able to compile the code the normal C++ way, using g++ or clang, so that I get object or ...
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2answers
513 views

Convert string to float or double

I am trying to convert a string to a float or double, however none of the standard C/C++ methods seem to work. I have tried: atof strtof strtod sscanf In each case, I get an error message when ...
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1answer
82 views

How to retrieve data from multi index table? i a=have stored data dynamically using emplace method now how to get it back as a Record?

I have used this code to store the data(name and marks) in the table, now i want to retrieve that data in the form of record. how can i get that? void addmarks(account_name examiner, account_name ...
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1answer
160 views

Error 30700002: Smart contract's apply function not exported; non-existent; or wrong type

I have written a smart contract and I want to start testing it, it contains an apply function, which currently checks for a transfer, and then calls the appropriate function: void mycontract::apply(...
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3answers
854 views

Which IDE can I use for EOS C++ source code?

What I need is an IDE as advanced as Eclipse, that would tell me if certain imports are missing, variables not declared, compile errors, and so on... I am using Linux so Visual Studio won't work for ...
3
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2answers
272 views

Building smart contract error: redefinition of 'time' as different kind of symbol typedef uint32_t time;

I am pretty desperate at this point to search for hints on this issue, though I am pretty sure it's because I'm new to C++ include system. I am getting an error while trying to run a wasm executable ...
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1answer
115 views

How to get current RAM price inside a contract in C++?

How can I programatically get the current(last) RAM price inside an EOS smart contract in C++? I need to handle the data inside the smart contract for an experiment.
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1answer
108 views

how to create an account except the way of using cleos?

guys!I am a beginner of eos. As it is said on the title, i want to create accounts by the way other than using cleos. I have traversed the doc of eos, but not seen the interface to create an account ...
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2answers
147 views

Setting up C++ developing environment

I'm a C++ dev and spent last months trying out solidity stuff but defintely want to try EOS now. How do I get started to understand all the terms and various parts of EOS ? I've seen gas works ...
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2answers
238 views

What libraries are supported by contracts?

What libraries can be used when writing a contract in C++? What are the limitations? If I have a library I normally use and like, how do I compile it for use by contracts?
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1answer
172 views

How can I call third party APIs from inside a smart contract at a set time or interval?

In a scenario where a smart contract needs to check against a third party service (Let's say an API with weather information from a trusted source like Weather.com) and make a decision on moving ...
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2answers
342 views

Which version of C++ can I use in smart contracts?

Which version of C++ can I use to implement smart contracts? For example: C++11, C++14 or C++17? Do we have any constant or doc where it is defined? Also, in my understanding the code is sandboxed, ...