Free() function in C language

Use malloc() and free() when dynamically allocating memory in C language.

One question is, how does the free function know the memory size dynamically allocated using malloc and solve the dynamic allocation?

#include <stdlib.h>
#include <iostream>
int main(){
    using namespace std;

    void* p;
    p = malloc(16);
    cout << p << "\n";
    cout << p+16 << "\n"

    free(p);
    cout << p << "\n";
    cout << p+16 << "\n"

}

Is the size of the dynamically allocated memory stored anywhere?

How do you protect dynamically allocated memory in the first place, and how does the free function unprotect the protected memory?

I'd appreciate it if you could let me know.