Parsing, editing and outputting JSON in C can be easily accomplished using facil.io's dynamic types (fiobj_s).
There are faster alternatives as well as slower 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 a framework wide object type (FIOBJ) 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; }