# bin/set-u32
Return a copy of `$bytes` with an unsigned 32-bit integer
written at `offset` (little-endian).
Byte strings are immutable — the original `$bytes` is unchanged.
## Syntax
[bin/set-u32 $bytes $offset $value]
## Parameters
- `$bytes` — byte string to copy and write into
- `$offset` — 0-based byte offset
- `$value` — value to write; clamped to the 32-bit range and truncated toward zero
## Examples
def buf [bin/set-u32 [bin/zeros 4] 0 70000] [bin/u32-at $buf 0] # → 70000 [bin/u8-at $buf 0] # → 112
## Returns
New byte string. A negative or out-of-bounds offset returns `%Err{:message}`.
## See Also
`bin/u32-at`, `bin/set-u32-be`, `bin/set-bytes`, `bin/bytes`