# Standard Library
Standard library is a set of built-in functions, structures and variables.
The version of the Standard library in the script is set by the STDLIB_VERSION directive.
We recommend to use version 4 of the Standard Library when developing applications.
⚠️ Standard library version 4 becomes available since node version 1.2.0, after activation of feature #15 “Ride V4, VRF, Protobuf, Failed transactions”.
Changes in versions are shown in the table.
| # | Version 3 | Version 4 |
|---|---|---|
| Script | Added: • dApp script • Directives • Annotations • Custom functions • FOLD<N> macro | |
| Data types | Added: • List | |
| Built-in variables | Added: • this • lastBlock • nil • Rounding methods: CEILING, DOWN, FLOOR etc. • Designations of hashing algorithms: NOALG, MD5, SHA1 etc. | |
| Structures | Added: Script actions: • DataEntry • ScriptTransfer Script results: • ScriptResult • TransferSet • WriteSet Common structures: • Asset • AttachedPayment • BlockInfo • Invocation Transaction structures: • InvokeScriptTransaction | Added: Script actions: • BinaryEntry • BooleanEntry • IntegerEntry • StringEntry • DeleteEntry • Issue • Reissue • Burn • SponsorFee Common structures: • BalanceDetails Transaction structures: • UpdateAssetInfoTransaction Modified: Common structures: • Asset • BlockInfo • Invocation Transaction structures: • DataTransaction • InvokeScriptTransaction • IssueTransaction Deleted: • DataEntry • ScriptResult • TransferSet • WriteSet |
| Built-in functions | Added: Blockchain functions: • assetInfo • blockInfoByHeight • transferTransactionById Converting functions: • parseInt • parseIntValue • toInt • toUtf8String • toString(Address) Decoding functions: • fromBase16String Encoding fuctions: • toBase16String Math functions: • log • pow String functions: • indexOf • lastIndexOf • split Union functions: • value • valueOrErrorMessage Verification functions: • checkMerkleProof • rsaVerify Deleted: • transactionById | Added: Blockchain functions: • calculateAssetId Converting fuctions: • transferTransactionFromProto List functions: • containsElement • indexOf • lastIndexOf • min/max • removeByIndex Math functions: • median String functions: • contains • makeString Union functions: • valueOrElse Verification functions: • bn256groth16verify • createMerkleRoot • ecrecover • groth16verify Deleted: • checkMerkleProof • extract |
| Operators | Added: • :+ • ++ | |
| Complexity changes | • - operator: 9 → 1 • ! operator: 11 → 1 • != operator: 26 → 1 • throw: 2 → 1 • isDefined: 35 → 1 | • + operator: 10 → 2 for ByteVector values, 10 → 20 for strings • Functions: see complexity changes in the Built-in Functions article • Added blake2b256_<N>Kb, keccak256_<N>Kb, sha256_<N>Kb, rsaVerify_<N>Kb, sigVerify_<N>Kb range of similar functions with different complexity depending on the argument size limit |
| Data size | • String: up to 32,767 bytes• ByteVector: up to 32,767 (except the bodyBytes field of the transaction structure) | |
| Proofs verification if the verifier function of dApp is defined | Proofs are not checked additionally | The first proof must be a valid sender's signature |