json-gen-c  0.1.5
json-gen-c generate C code for json manipulation
Getting Started with json-gen-c

This guide walks you through installing json-gen-c, generating code, and integrating it into your project.

Prerequisites

  • A C11-compatible compiler (GCC or Clang).
  • GNU Make.
  • Optional: pkg-config, clang-format, and cppcheck for a smoother workflow.

1. Install json-gen-c

git clone https://github.com/zltl/json-gen-c.git
cd json-gen-c
make
sudo make install # optional, installs json-gen-c into your PATH

2. Describe Your Data

Create a .json-gen-c file describing the structs to serialize:

// file: demo.json-gen-c
struct User {
int id;
sstr_t name;
double balance;
Address address;
};
struct Address {
sstr_t city;
sstr_t country;
};
sstr_t
void * sstr_t
sstr_t are objects that represent sequences of characters.
Definition sstr.h:74

3. Generate Code

json-gen-c -in demo.json-gen-c -out gen

The command emits:

  • gen/json.gen.h / gen/json.gen.c – struct definitions and JSON helpers.
  • gen/sstr.h / gen/sstr.c – lightweight string utilities required by the generated code.

4. Use the Generated API

#include "json.gen.h"
int main(void) {
struct User user;
User_init(&user);
user.id = 7;
user.name = sstr("Ada");
sstr_t payload = sstr_new();
json_marshal_User(&user, payload);
printf("%s\n", sstr_cstr(payload));
sstr_free(payload);
User_clear(&user);
return 0;
}
sstr
sstr_t sstr(const char *cstr)
Create a sstr_t from C-style (NULL-terminated) string str.
Definition sstr.c:84
sstr_new
sstr_t sstr_new()
Create an empty sstr_t.
Definition sstr.c:42
sstr_free
void sstr_free(sstr_t s)
delete a sstr_t.
Definition sstr.c:48
sstr_cstr
char * sstr_cstr(sstr_t s)
Return C-style string representation of s.
Definition sstr.c:86

Link your program with the generated json.gen.c and sstr.c files.

5. Regenerate on Schema Changes

Any time you edit the .json-gen-c schema, rerun json-gen-c to refresh the generated sources. Consider automating this step with a Makefile target so your build always has up-to-date code.

6. Learn More

  • Browse the example/ directory for reference schemas and usage.
  • Run json-gen-c --help to see command-line options.
  • Consult the online documentation for API details.

Happy hacking! 🎉