Very simple JSON parser for C++

A single header + implementation file JSON parser. Drop jute.h and jute.cpp into your project and go.

Build

make        # builds the example binary
make test   # builds and runs the test suite
make clean  # removes compiled binaries

Or compile manually:

g++ -std=c++17 -o jute main.cpp jute.cpp

Quick start

#include "jute.h"

int main() {
    // Parse a JSON string
    jute::jValue v = jute::parser::parse(R"({"name": "jute", "version": 1})");
    std::cout << v["name"].as_string() << "\n"; // jute
    std::cout << v["version"].as_int() << "\n"; // 1

    // Or load from a file
    jute::jValue file_v = jute::parser::parse_file("data.json");
    std::cout << file_v.to_string() << "\n";
}

API reference

All accessor methods are const — jValue is designed as a read-only view into parsed JSON.

Method	Returns	Description
get_type()	jType	One of JSTRING, JOBJECT, JARRAY, JBOOLEAN, JNUMBER, JNULL, JUNKNOWN
as_string()	std::string	String value with escape sequences deserialized
as_int()	int	Number as integer
as_double()	double	Number as double
as_bool()	bool	Boolean value
as_null()	void*	Returns nullptr
size()	size_t	Number of array elements or object properties
operator[](size_t i)	const jValue&	Access array element by index
operator[](string s)	const jValue&	Access object property by key
to_string()	std::string	Pretty-print back to JSON

Accessing a missing key or out-of-bounds index returns a jValue with type JUNKNOWN (no crash).

data.json example

{
  "examples": [
    {
      "tag_name": "a",
      "attr": [
        { "key": "href",   "value": "http://example.com" },
        { "key": "target", "value": "_blank" }
      ]
    },
    {
      "this_is": ["array", "of", "strings"],
      "number_array": [1, 2, 4, 8, 16],
      "pie": 3.14,
      "boolean": true,
      "bug": null,
      "mixed": [1, 2, {"test1": -1.2345, "test2": false}, null, 0.4, ["nested", ["array", true]], "end of story!"]
    },
    { "done": true }
  ]
}

Note

This library does not perform error checking — it assumes the input is valid JSON. For production use, consider a more complete library. PRs are welcome!

License: MIT