Overview

In Qubic, smart contracts are implemented in a restricted variant of C++ and compiled into the Qubic Core executable.

To isolate contracts, access to other contracts and Core internals is only allowed via the QPI (Qubic Programming Interface), the sole external dependency permitted. Using libraries is forbidden. Contracts also cannot use insecure C++ features like pointers, low-level arrays (no bounds checking), or preprocessor directives. All memory is zero-initialized, so contracts never access uninitialized memory.

A contract has a state struct, containing all its data as member variables. The memory available to the contract is allocated statically, but extending the state will be possible between epochs through special EXPAND events.

Important considerations for contract developers:

• Contract execution incurs fees, paid from an execution fee reserve funded by QUs burned during the IPO and through ongoing burns. A contract must continue burning QUs to stay active—once the reserve is empty, it stops executing. See Contract Execution Fees for details.