Text Processing

Character Encoding

By default, this library supports UTF-8 encoding without a BOM, as specified in RFC 8259:

JSON text exchanged between systems that are not part of a closed ecosystem MUST be encoded using UTF-8. Implementations MUST NOT add a byte order mark (U+FEFF) to the beginning of a networked-transmitted JSON text.

This library performs strict UTF-8 encoding validation on input strings by default. If an invalid character is encountered, an error will be reported.

To allow a BOM, use the YYJSON_READ_ALLOW_BOM or YYJSON_READ_ALLOW_EXT_WHITESPACE flags.

To allow invalid Unicode encoding, use the YYJSON_READ_ALLOW_INVALID_UNICODE and YYJSON_WRITE_ALLOW_INVALID_UNICODE flags. Note: Enabling these flags may result in yyjson producing values that contain invalid characters, which could be processed by other code and potentially introduce security risks.

To mark a string as not requiring escaping during JSON writing, use yyjson_set_str_noesc(yyjson_val *val, bool noesc) or yyjson_mut_set_str_noesc(yyjson_mut_val *val, bool noesc). This can improve string-writing performance and preserve the original string bytes.

NUL Character

This library supports the NUL character (also known as the null terminator, or Unicode U+0000, ASCII \0) inside strings.

When reading JSON, \u0000 will be unescaped to NUL character. If a string contains the NUL character, the length obtained with strlen() will be inaccurate, and you should use yyjson_get_len() to get the actual length.

When building JSON, the input string is treated as null-terminated by default. If you need to pass in a string that contains the NUL character, you should use the API with the n suffix and provide the actual length of the string.

For example:

// null-terminated string
yyjson_mut_str(doc, str);
yyjson_obj_get(obj, str);

// any string, with or without null terminator
yyjson_mut_strn(doc, str, len);
yyjson_obj_getn(obj, str, len);

// C++ string
std::string sstr = ...;
yyjson_obj_getn(obj, sstr.data(), sstr.length());