BSON_APPEND_REGEX_W_LEN(3)

✨ hey bestie, meet bson_append_regex_w_len ✨

okay so this is a page from libbson, section 3 of the manual — it's all about bson_append_regex_w_len, and honestly it's giving "small function, big responsibilities" 💅. Let's get into it fr fr.

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🌸 SYNOPSIS 🌸

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

that's the whole signature, no cap. six params, one bool back. let's meet the cast 🫶

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🎀 PARAMETERS 🎀

• bson — a bson_t. the doc you're stuffing a field into. your main character, literally.
• key — an ASCII C string holding the name of the field. keep it ASCII bestie, no funny business.
• key_length — how long key is, in bytes. or pass -1 and it'll just figure it out with strlen(). lazy girl summer, and honestly? valid.
• regex — an ASCII string with the regex in it. the actual pattern, the whole point of the function 💖
• regex_length — the length of regex in bytes, or -1 to let strlen() do the counting for you. same deal as above ✨
• options — an optional string with the regex options, as a string. optional optional, like you can hand it over or not 🦋

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💅 DESCRIPTION 💅

so what it does: it appends a brand-new field to bson, and that field is of type BSON_TYPE_REGEX 👑. regex should be the regex string, and options should carry the options for that regex.

the valid characters you can put in options are:

• '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.

like, that's the whole menu. those six lil letters, each one doing its own iconic thing 🌈

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⭐ RETURNS ⭐

returns true if the operation was applied successfully 🎉.

and here's the not-so-slay part: the function will fail if appending the regex grows bson larger than INT32_MAX. that's the ceiling, and she is real 😭 so check that return value, bestie, don't just assume it ate.

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🦋 AUTHOR 🦋

MongoDB, Inc — the ones who brought you this whole situation 💜

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🧚 COPYRIGHT 🧚

2009-present, MongoDB, Inc. — periodt, respect the copyright line fr fr 🙈

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and that's the page!! source/version 2.5.6, dated Oct 09, 2026, straight out of the libbson BSON_APPEND_REGEX_W_LEN(3) manual 🎀 ok bye, go append some regexes responsibly 💖