Parsing, editing and outputting JSON in C can be easily accomplished using facil.io's dynamic types (fiobj_s).
There are faster alternatives out there (i.e., the C++ RapidJSON is much faster).
However, facil.io offers the added benefit of complete parsing from JSON to object. This is in contrast to some parsers that offer a mid-way structure (often a linked list of JSON nodes) or lazy (delayed) parsing for types such as true, false and Numbers.
facil.io also offers the added benefit of complete formatting from object to JSON. This is in contrast to some solutions that require a linked list of node structures.
The facil.io parser will parse any C string until it either consumes the whole string or completes parsing of a JSON object.
For example, the following program will minify (or prettify) JSON data:
// include the `fiobj` module from `facil.io` #include "fiobj.h" #include <string.h> // this is passed as an argument to `fiobj_obj2json` // change this to 1 to prettify. #define PRETTY 0 int main(int argc, char const *argv[]) { // a default string to demo const char * json = u8"{\n\t\"id\":1,\n" "\t// comments are ignored.\n" "\t\"number\":42,\n" "\t\"float\":42.42,\n" "\t\"string\":\"𝄞 oh yeah...\",\n" "\t\"hash\":{\n" "\t\t\"nested\":true\n" "\t},\n" "\t\"symbols\":[\"id\"," "\"number\",\"float\",\"string\",\"hash\",\"symbols\"]\n}"; if (argc == 2) { // accept command line JSON data json = argv[1]; } printf("\nattempting to parse:\n%s\n", json); // actual code for parsing the JSON FIOBJ obj; size_t consumed = fiobj_json2obj(&obj, json, strlen(json)); // test for errors if (!obj) { printf("\nERROR, couldn't parse data.\n"); exit(-1); } // format the JSON back to a String object and print it up FIOBJ str = fiobj_obj2json(obj, PRETTY); printf("\nParsed JSON input was: %lu bytes" "\nJSON output is %lu bytes:\n\n%s\n\n", consumed, (size_t)fiobj_obj2cstr(str).len, fiobj_obj2cstr(str).data); // cleanup fiobj_free(str); fiobj_free(obj); return 0; }