inih (INI Not Invented Here) is a simple .INI file parser written in C. It's only a couple of pages of code, and it was designed to be small and simple, so it's good for embedded systems. It's also more or less compatible with Python's ConfigParser style of .INI files, including RFC 822-style multi-line syntax and name: value entries.

To use it, just give ini_parse() an INI file, and it will call a callback for every name=value pair parsed, giving you strings for the section, name, and value. It's done this way because it works well on low-memory embedded systems, but also because it makes for a KISS implementation.

Download inih now, browse the source, or read about how to use inih in a DRY style with X-Macros.

Simple example in C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../ini.h"

typedef struct
{
    int version;
    const char* name;
    const char* email;
} configuration;

static int handler(void* user, const char* section, const char* name,
                   const char* value)
{
    configuration* pconfig = (configuration*)user;

    #define MATCH(s, n) stricmp(section, s) == 0 && stricmp(name, n) == 0
    if (MATCH("protocol", "version")) {
        pconfig->version = atoi(value);
    } else if (MATCH("user", "name")) {
        pconfig->name = strdup(value);
    } else if (MATCH("user", "email")) {
        pconfig->email = strdup(value);
    } else {
        return 0;  /* unknown section/name, error */
    }
    return 1;
}

int main(int argc, char* argv[])
{
    configuration config;

    if (ini_parse("test.ini", handler, &config) < 0) {
        printf("Can't load 'test.ini'\n");
        return 1;
    }
    printf("Config loaded from 'test.ini': version=%d, name=%s, email=%s\n",
        config.version, config.name, config.email);
    return 0;
}

C++ example

If you're into C++ and the STL, there is also an easy-to-use INIReader class that stores values in a map and lets you Get() them:

#include <iostream>
#include "INIReader.h"

int main()
{
    INIReader reader("../examples/test.ini");

    if (reader.ParseError() < 0) {
        std::cout << "Can't load 'test.ini'\n";
        return 1;
    }
    std::cout << "Config loaded from 'test.ini': version="
              << reader.GetInteger("protocol", "version", -1) << ", name="
              << reader.Get("user", "name", "UNKNOWN") << ", email="
              << reader.Get("user", "email", "UNKNOWN") << ", active="
              << reader.GetBoolean("user", "active", true) << "\n";
    return 0;
}