Struct DataWriter 

pub struct DataWriter<'a> { /* private fields */ }

Zero-copy write cursor over a mutable byte slice.

Position-tracked and bounds-checked. Use this when initializing a new account’s data layout inside a create instruction - it replaces the error-prone pattern of tracking byte offsets by hand.

let mut raw = account.try_borrow_mut()?;
let mut w = DataWriter::new(&mut *raw);
w.write_u8(MY_DISC)?;         // discriminator
w.write_u64(0)?;               // initial balance
w.write_address(&authority)?;  // 32-byte pubkey

All writes are little-endian, matching the convention used by Solana’s instruction data encoding and most on-chain programs.

Implementations

impl<'a> DataWriter<'a>

pub fn new(data: &'a mut [u8]) -> Self

pub fn written(&self) -> usize

Number of bytes written so far.

pub fn write_u8(&mut self, val: u8) -> Result<(), ProgramError>

pub fn write_u16(&mut self, val: u16) -> Result<(), ProgramError>

pub fn write_u32(&mut self, val: u32) -> Result<(), ProgramError>

pub fn write_u64(&mut self, val: u64) -> Result<(), ProgramError>

pub fn write_i64(&mut self, val: i64) -> Result<(), ProgramError>

pub fn write_bool(&mut self, val: bool) -> Result<(), ProgramError>

Writes 1u8 for true, 0u8 for false.

pub fn write_address(&mut self, addr: &Address) -> Result<(), ProgramError>

pub fn write_i8(&mut self, val: i8) -> Result<(), ProgramError>

pub fn write_i16(&mut self, val: i16) -> Result<(), ProgramError>

pub fn write_i32(&mut self, val: i32) -> Result<(), ProgramError>

pub fn write_u128(&mut self, val: u128) -> Result<(), ProgramError>

Write a u128 (16 bytes, little-endian).

pub fn write_i128(&mut self, val: i128) -> Result<(), ProgramError>

Write an i128 (16 bytes, little-endian).