---
name: "bson_append_utf8"
section: "3"
platform: "linux"
package: "libbson-doc"
version: "1.30.4-1+deb13u3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/bson_append_utf8"
---

# bson\_append\_utf8(3)

## SYNOPSIS

```
#define BSON_APPEND_UTF8(b, key, val) \
   bson_append_utf8 (b, key, (int) strlen (key), val, (int) strlen (val))
bool
bson_append_utf8 (bson_t *bson,
                  const char *key,
                  int key_length,
                  const char *value,
                  int length);
```

## PARAMETERS

- •

  **bson**: A *bson\_t*.

- •

  **key**: An ASCII C string containing the name of the field.

- •

  **key\_length**: The length of **key** in bytes, or -1 to determine the length with **strlen()**.

- •

  **value**: A UTF-8 encoded string.

- •

  **length**: The number of bytes in **value** excluding the trailing **\\0**, or -1 to determine the length with **strlen()**.

## DESCRIPTION

The *bson\_append\_utf8()* function shall append a UTF-8 encoded string to **bson**.

**value** *MUST* be valid UTF-8.

Some UTF-8 implementations allow for **\\0** to be contained within the string (excluding the termination **\\0**. This is allowed, but remember that it could cause issues with communicating with external systems that do not support it.

It is suggested to use modified UTF-8 which uses a 2 byte representation for embedded **\\0** within the string. This will allow these UTF-8 encoded strings to used with many libc functions.

Due to legacy behavior, passing **NULL** for **value** appends a null value, *not* a UTF8 value. To append a null value directly, prefer using *bson\_append\_null()*.

## RETURNS

Returns **true** if the operation was applied successfully. The function will fail if appending the value grows **bson** larger than INT32\_MAX.

## AUTHOR

MongoDB, Inc

## COPYRIGHT

2009-present, MongoDB, Inc.