我不明白 inih 是如何工作的

Question

I've been trying to read an ini file with inih lib since a few hours, and I still don't totally understand this code, especially configuration* pconfig = (configuration*)user; , and what are the handler function parameters for?

#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) strcmp(section, s) == 0 && strcmp(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;
}

Answer 1

user is a "generic pointer", or "untyped pointer".

Dereferencing that pointer would give you a value of type void which isn't possible.

Therefore you must cast the pointer to the correct type to be able to use it.

---

As for the arguments and what they're used for you could read the source .

But with a little knowledge of INI files it should be easy to deduce that the section argument is the name of a section in the file, while name is the current value name, and value is the value itself.

So assuming a section and value like

[foo]
bar = something

Then section would be "foo" , name would be "bar" and value would be "something" .

And the user argument is very likely the third argument passed to ini_parse .

Answer 2

user is obviously a pointer to configuration instance you gave to ini_parse . void* is only kind of type erasure for pointers available in C.

section is name of section of.ini file, name is key name, value is key's value.

ini_parse calls handler for every key, passing it configuration and result of parsing iteration. What handler does with that information, is to be defined by user of library.