How does this C copy function exit its loop?

Question

void copy (char *source, char *dest) {
    while (*dest++ = *source++);
}

The char that is represented by *source is copied to the field <

Answer 1

The 'result' of an assignment is the right-hand value. So x=1; actually returns a value; in this case, '1'.

Your code copies characters until it encountered the terminating 0 at the end of the source string.