---
name: "bson_array_builder_t"
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_array_builder_t"
---

# bson\_array\_builder\_t(3)

```
typedef struct _bson_array_builder_t bson_array_builder_t;
```

**bson\_array\_builder\_t** may be used to build BSON arrays. **bson\_array\_builder\_t** internally tracks and uses the array index as a key ("0", "1", "2", ...) when appending elements.

## APPENDING AN ARRAY VALUE

```
typedef struct _bson_array_builder_t bson_array_builder_t;
bool
bson_append_array_builder_begin (bson_t *bson,
                                 const char *key,
                                 int key_length,
                                 bson_array_builder_t **child);
bool
bson_append_array_builder_end (bson_t *bson, bson_array_builder_t *child);
#define BSON_APPEND_ARRAY_BUILDER_BEGIN(b, key, child) \
  bson_append_array_builder_begin (b, key, (int) strlen (key), child)
```

**bson\_append\_array\_builder\_begin** may be used to append an array as a value. Example:

```
bson_t parent = BSON_INITIALIZER;
bson_array_builder_t *bab;
bson_append_array_builder_begin (&parent, "foo", 3, &bab);
bson_array_builder_append_int32 (bab, 9);
bson_array_builder_append_int32 (bab, 8);
bson_array_builder_append_int32 (bab, 7);
bson_append_array_builder_end (&parent, bab);
char *str = bson_as_relaxed_extended_json (&parent, NULL);
printf ("%s\n", str); // Prints: { "foo" : [ 9, 8, 7 ] }
bson_free (str);
bson_destroy (&parent);
```

## CREATING A TOP-LEVEL ARRAY

```
bson_array_builder_t * bson_array_builder_new (void);
bool
bson_array_builder_build (bson_array_builder_t *bab, bson_t *out);
void
bson_array_builder_destroy (bson_array_builder_t *bab);
```

**bson\_array\_builder\_new** and **bson\_array\_builder\_build** may be used to build a top-level BSON array. **bson\_array\_builder\_build** initializes and moves BSON data to **out**. The **bson\_array\_builder\_t** may be reused and will start appending a new array at index "0":

Example:

```
bson_t out;
bson_array_builder_t *bab = bson_array_builder_new ();
bson_array_builder_append_int32 (bab, 9);
bson_array_builder_append_int32 (bab, 8);
bson_array_builder_append_int32 (bab, 7);
bson_array_builder_build (bab, &out);
char *str = bson_array_as_relaxed_extended_json (&out, NULL);
printf ("%s\n", str); // Prints: [ 9, 8, 7 ]
bson_free (str);
bson_array_builder_destroy (bab);
```

## APPENDING VALUES TO AN ARRAY

**bson\_array\_builder\_append\_\*** functions are provided to append values to a BSON array. The **bson\_array\_builder\_append\_\*** functions internally use **bson\_append\_\*** and provide the array index as a key:

```
bool
bson_array_builder_append_value (bson_array_builder_t *bab,
                                 const bson_value_t *value);
bool
bson_array_builder_append_array (bson_array_builder_t *bab,
                                 const bson_t *array);
bool
bson_array_builder_append_binary (bson_array_builder_t *bab,
                                  bson_subtype_t subtype,
                                  const uint8_t *binary,
                                  uint32_t length);
bool
bson_array_builder_append_bool (bson_array_builder_t *bab, bool value);
bool
bson_array_builder_append_code (bson_array_builder_t *bab,
                                const char *javascript);
bool
bson_array_builder_append_code_with_scope (bson_array_builder_t *bab,
                                           const char *javascript,
                                           const bson_t *scope);
bool
bson_array_builder_append_dbpointer (bson_array_builder_t *bab,
                                     const char *collection,
                                     const bson_oid_t *oid);
bool
bson_array_builder_append_double (bson_array_builder_t *bab, double value);
bool
bson_array_builder_append_document (bson_array_builder_t *bab,
                                    const bson_t *value);
bool
bson_array_builder_append_document_begin (bson_array_builder_t *bab,
                                          bson_t *child);
bool
bson_array_builder_append_document_end (bson_array_builder_t *bab,
                                        bson_t *child);
bool
bson_array_builder_append_int32 (bson_array_builder_t *bab, int32_t value);
bool
bson_array_builder_append_int64 (bson_array_builder_t *bab, int64_t value);
bool
bson_array_builder_append_decimal128 (bson_array_builder_t *bab,
                                      const bson_decimal128_t *value);
bool
bson_array_builder_append_iter (bson_array_builder_t *bab,
                                const bson_iter_t *iter);
bool
bson_array_builder_append_minkey (bson_array_builder_t *bab);
bool
bson_array_builder_append_maxkey (bson_array_builder_t *bab);
bool
bson_array_builder_append_null (bson_array_builder_t *bab);
bool
bson_array_builder_append_oid (bson_array_builder_t *bab,
                               const bson_oid_t *oid);
bool
bson_array_builder_append_regex (bson_array_builder_t *bab,
                                 const char *regex,
                                 const char *options);
bool
bson_array_builder_append_regex_w_len (bson_array_builder_t *bab,
                                      const char *regex,
                                      int regex_length,
                                      const char *options);
bool
bson_array_builder_append_utf8 (bson_array_builder_t *bab,
                                const char *value,
                                int length);
bool
bson_array_builder_append_symbol (bson_array_builder_t *bab,
                                  const char *value,
                                  int length);
bool
bson_array_builder_append_time_t (bson_array_builder_t *bab, time_t value);
bool
bson_array_builder_append_timeval (bson_array_builder_t *bab,
                                   struct timeval *value);
bool
bson_array_builder_append_date_time (bson_array_builder_t *bab, int64_t value);
bool
bson_array_builder_append_now_utc (bson_array_builder_t *bab);
bool
bson_array_builder_append_timestamp (bson_array_builder_t *bab,
                                     uint32_t timestamp,
                                     uint32_t increment);
bool
bson_array_builder_append_undefined (bson_array_builder_t *bab);
bool
bson_array_builder_append_array_builder_begin (bson_array_builder_t *bab,
                                               bson_array_builder_t **child);
bool
bson_array_builder_append_array_builder_end (bson_array_builder_t *bab,
                                             bson_array_builder_t *child);
```

## AUTHOR

MongoDB, Inc

## COPYRIGHT

2009-present, MongoDB, Inc.