This page is used to describe all the additional APIs which exists as part of the Contract SDK.
To use the
Env package, you need to import it:
It provides the following functions:
Used to get the block height which will be the one this transaction be a part of
It returns the block height in decimal values:
Used to get the block timestamp (creation time) which will be the one this transaction be a part of:
It returns the block timestamp representing the Unix epoch in nanoseconds.
Used to get the block proposer address, which is the address of the node who wrote the block or is trying to write the block right now. When called during a RunQuery operation, the address the Node that generated this block is 'read' from the block itself, this is the case where data is read from the chain and not written to it, so the block already exists. When called during a SendTransaction operation the Node that is trying to generate the block with the transaction will set its own address as block proposer.
It will return the block proposer address as a byte array
Used to get the virtual chain id this contract is executing on.
It returns the virtual chain id in decimal values.
To use the
Safemath package, you need to import it:
It gives the ability to work with 32, 64, and 256 bit unsigned integers in a 'safe' way meaning there is an overflow/underflow and illegal operation protection around the arithmetic operation done.
The API is uniform between the different variants and consist of the following functions:
Adds two numbers and returns the result. The numbers are validated so that they do not overflow after the addition.
Add(x *big.Int, y *big.Int) *big.IntAdd(x uint32, y uint32) uint32Add(x uint64, y uint64) uint64
x. The result is validated, so if it becomes negative, an error is returned.
Sub(x *big.Int, y *big.Int) *big.IntSub(x uint32, y uint32) uint32Sub(x uint64, y uint64) uint64
Multiplies the values and returns the new number. The result is validated so that it does not overflow.
Mul(x *big.Int, y *big.Int) *big.IntMul(x uint32, y uint32) uint32Mul(x uint64, y uint64) uint64
Performs an integer division of
y. The remainder is discarded as it should in integer arithmetic, and the input (
y) is validated not to be zero.
Div(x *big.Int, y *big.Int) *big.IntDiv(x uint32, y uint32) uint32Div(x uint64, y uint64) uint64
Performs the modulo operation of
y. The input is validated to be valid (meaning
y is not zero). The resulting number is the reminder.
Mod(x *big.Int, y *big.Int) *big.IntMod(x uint32, y uint32) uint32Mod(x uint64, y uint64) uint64
The function validates that the number is not negative, and did not overflow. If the validation fails, the code panics with the appropriate message.
validate is called automatically on each operation, meaning after using
Sub or any operation of the safemath library, so there is no need to call it manually.