jenny is a JSON generator.

jenny is built first and foremost for embedded applications where the heap is limited and you generally want to avoid allocations. malloc() is not used here!

Here's how it works:

First, you define your JSON structure and what variables you want in it. For example, here is test.jenny:

{
    "int": "$this_is_an_int, int$",
    "string": "$this_is_a_string, string$"
}

(By the way, you can use a JSON validator to check that this is valid JSON. jenny does not check!)

Then, you use ./jenny to generate a .c file:

./jenny < test.jenny
{
    { .type = JENNY_CHUNK, .u.chunk = "{\n    \"int\": "},
    { .type = JENNY_VAR, .u.var = { .p = &this_is_an_int, .type = JENNY_INT_TYPE }},
    { .type = JENNY_CHUNK, .u.chunk = ",\n    \"string\": "},
    { .type = JENNY_VAR, .u.var = { .p = &this_is_a_string, .type = JENNY_STRING_TYPE }},
    { .type = JENNY_CHUNK, .u.chunk = "\n}\n"},
    { .type = JENNY_END }
}

Then, you #include the C file and use the jenny API to output the JSON to any write() -ish function that you want. In this case, I'm wrapping write itself to print to STDOUT:

#include <unistd.h>

#include "jenny.h"

int this_is_an_int = 20;
char *this_is_a_string = "\"abc\n\t\\123";
jenny_t test[] =
#include "test.jenny.c"

ssize_t write_wrapper(void *p_fd, const void *p, size_t len) {
    return write(*(int *)p_fd, p, len);
}

int main(void) {
    int fd = STDOUT_FILENO;
    jenny(test, write_wrapper, &fd);

    return 0;
}