#define BSON_APPEND_REGEX(b, key, val, opt) \

       MongoDB, Inc

       2009-present, MongoDB, Inc.

1.30.4                                            Jun 08, 2025                              BSON_APPEND_REGEX(3)

       Appends  a  new  field  to bson of type BSON_TYPE_REGEX. regex should be the regex string. options should
       contain the options for the regex.

       Valid characters for options include:

       • 'i' for case-insensitive.

       • 'm' for multiple matching.

       • 'x' for verbose mode.

       • 'l' to make w and W locale dependent.

       • 's' for dotall mode ('.' matches everything)

       • 'u' to make w and W match unicode.

       • 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().

       • regex: An ASCII string containing the regex.

       • options: An optional string containing the regex options as a string.

       Returns true if the operation was applied successfully. The function will fail  if  appending  the  regex
       grows bson larger than INT32_MAX.

          #define BSON_APPEND_REGEX(b, key, val, opt) \
             bson_append_regex (b, key, (int) strlen (key), val, opt)

          bool
          bson_append_regex (bson_t *bson,
                             const char *key,
                             int key_length,
                             const char *regex,
                             const char *options);