Unexpected answer in c++

Question

i wrote this code in c++. i expect 4932.08 for the answer(calculated by calculator)

#include <iostream>
#include <float.h>
#include <math.h>
    
using namespace std;
    
int main()
{
    long double a;
    a = LDBL_MAX;
    cout << "log10(" << a << ") = " << log10(a);    
}

sizeof(a) = 16 Bytes on my computer

instead of getting the correct answer, the output was inf. what is the problem? is it about the sizeof data log10 can get? what should i do to get correct answer?

I run this code with DEV and g++ (MinGW) by CMD. results are interesting.

DEV: inf

MinGW: 4932.08

sizeof(a):

dev: 16

MinGW: 12

why???

thank you