How to retrieve value from bytes stored in a byte array?

Question

I am trying to store 8 bytes in a byte array to store the value of a pointer.

int main() {
    unsigned long a = 0;
    char buf[8];
    int i = 0;
    int *p = &i;
    a = (unsigned long)p;

    while (i < 8)
    {
        buf[i] = (a >> (8 * i)) & 0xFF;
        i++;
    }
    a = 0;
    i = 0;
    while (i < 8)
    {
        a = ?
        i++;
    }
    p = (int *)a;
}

The first loop stores successive bytes of p, as casted into usigned long in a, but I don't know how to retrieve the value in the second loop. Does somebody have a clue?

Answer 1

This is the inverse code to yours:

a = 0;
while (i < 8)
{
    a |= ((unsigned long)buf[i] & 0xff ) << (8 * i);
    i++;
}