= nng_msg_header_insert(3) // // Copyright 2018 Staysail Systems, Inc. // Copyright 2018 Capitar IT Group BV // // This document is supplied under the terms of the MIT License, a // copy of which should be located in the distribution where this // file was obtained (LICENSE.txt). A copy of the license may also be // found online at https://opensource.org/licenses/MIT. // == NAME nng_msg_header_insert - 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_u16(nng_msg *msg, uint16_t val16); int nng_msg_header_insert_u32(nng_msg *msg, uint32_t val32); int nng_msg_header_insert_u64(nng_msg *msg, uint64_t val64); ---- == DESCRIPTION The `nng_msg_header_insert()` family of functions prepends data to the front of the headers of message _msg_, reallocating if necessary. The first function prepends _size_ bytes, copying them from _val_. The remaining functions prepend the specified value (such as _val32_) in network-byte order (big-endian). == RETURN VALUES These functions return 0 on success, and non-zero otherwise. == ERRORS [horizontal] `NNG_ENOMEM`:: Insufficient free memory exists. == SEE ALSO [.text-left] <>, <>, <>, <>, <>, <>, <>, <>, <>, <>