= nng_msg_header_insert(3) :doctype: manpage :manmanual: nng :mansource: nng :manvolnum: 3 :copyright: Copyright 2018 mailto:info@staysail.tech[Staysail Systems, Inc.] + \ Copyright 2018 mailto:info@capitar.com[Capitar IT Group BV] + \ {blank} + \ This document is supplied under the terms of the \ https://opensource.org/licenses/MIT[MIT License]. == NAME nng_msg_header_insert, nng_msg_header_insert_u32 - prepend to message header == SYNOPSIS [source, c] ----------- #include int nng_msg_header_insert(nng_msg *msg, const void *val, size_t size); int nng_msg_header_insert_u32(nng_msg *msg, uint32_t val32); ----------- == DESCRIPTION The `nng_msg_header_insert()` and `nng_msg_header_insert_u32()` functions prepend data to the front of the headers of message _msg_, reallocating if necessary. The first function prepends _size_ bytes, copying them from _val_. The second function prepends the value _val32_ in network-byte order (big-endian). == RETURN VALUES This function returns 0 on success, and non-zero otherwise. == ERRORS `NNG_ENOMEM`:: Insufficient free memory exists. == SEE ALSO <>, <>, <>, <>, <>, <>, <>, <>, <>, <> == COPYRIGHT {copyright}