= nng_msg_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_insert, nng_msg_insert_u32 - prepend to message body == SYNOPSIS [source, c] ----------- #include int nng_msg_insert(nng_msg *msg, const void *val, size_t size); int nng_msg_insert(nng_msg *msg, uint32_t val32); ----------- == DESCRIPTION The `nng_msg_insert()` and `nng_msg_insert_u32()` functions prepend data to the front of the body of message _msg_, reallocating it 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). TIP: This function makes use of pre-allocated "headroom" in the message if available, so it can often avoid performing any reallocation. Applications should use this instead of reallocating and copying message content themselves, in order to benefit from this capabilitiy. == RETURN VALUES This function returns 0 on success, and non-zero otherwise. == ERRORS `NNG_ENOMEM`:: Insufficient free memory exists. == SEE ALSO <>, <>, <>, <>, <>, <>, <>, <>, <>, <> == COPYRIGHT {copyright}