This page is used to describe all the additional API 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 will return 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 will return the block timestamp representing the Unix epoch in nanoseconds
Used to get the virtual chain id this contract is executing under
It will return 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 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 the integer division of
y. The remainder is discarded as it should in integer arithmetic and the input (
y) is validated to not 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 between
y. The input is validated to be valid (meaning
y is not zero to avoid invalid division) - the resulting number will hold the reminder as expected
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 validation fails, the code will panic with the appropriate message
It is called automatically on each operation, meaning after using
Sub or any operation of the safemath library, there is no need to manually validate.