## nng_msg_header_trim

Remove data from start of message header.

### Synopsis

```c
#include <nng/nng.h>

int nng_msg_header_trim(nng_msg *msg, size_t size);
int nng_msg_header_trim_u16(nng_msg *msg, uint16_t *val16);
int nng_msg_header_trim_u32(nng_msg *msg, uint32_t *val32);
int nng_msg_header_trim_u64(nng_msg *msg, uint64_t *val64);
```

### Description

These functions remove data from the start of the header of message _msg_.

The `nng_msg_header_trim` function removes _size_ bytes.
The remaining functions removes 2, 4, or 8 bytes, and stores them in the value (such as _val32_),
after converting them from network-byte order (big-endian) to native byte order.

### Return Values

This function returns 0 on success, and non-zero otherwise.

### Errors

[horizontal]
`NNG_EINVAL`:: The message header is too short to remove the requested data.

### See Also

xref:nng_msg_header.adoc[nng_msg_header],
xref:nng_msg_header_append.adoc[nng_msg_header_append],
xref:nng_msg_header_chop.adoc[nng_msg_header_chop],
xref:nng_msg_header_insert.adoc[nng_msg_header_insert],
xref:nng_msg_header_len.adoc[nng_msg_header_len],