io.file.writen

Method of file, from module "io"

instance.writen(value: number, format: int)

Writes a numeric value in the given format

examples/io/file/writen-basic.nut

from "io" import file
from "system" import getenv, remove

let path = $"{getenv("TEMP") ?? getenv("TMP") ?? "/tmp"}/qrl_io_file_writen_basic.tmp"
let f = file(path, "w+b")
f.writen(200, 'i')

f.seek(0)
println("f.readn('i') =", f.readn('i'))

f.close()
remove(path)

Output:

f.readn('i') = 200

Parameters

`value`	number	the value to write
`format`	int	a character selecting the type and size to write

Errors

Throws the stream is invalid once the file has been closed.

Notes

See iostream.stream.writen for the format codes, their sizes and the byte order used. Open with a b mode (see constructor) so no line-ending translation can land an unexpected byte in the middle of a value.

Example

examples/io/file/writen.nut

from "io" import file
from "system" import getenv, remove

let path = $"{getenv("TEMP") ?? getenv("TMP") ?? "/tmp"}/qrl_io_file_writen.tmp"
let f = file(path, "w+b")
f.writen(0x01020304, 'i')
println("f.len() after writen =", f.len())      // 4 bytes for a 32-bit 'i', same sizes as iostream.stream.writen

f.close()
remove(path)