Question

BigInt C++ constructors

bigint a(0); bigint b(a);

// Creates b from a. Yields two equivalent BigInts, both equal to 0 in this case. Yields two equivalent BigInts, both equal to 0 in this case.

bigint::bigint(const bigint &that) {

}

Answer 1

you have not shared the complete bigint class, due to which i am not able to figure out what are all the members in bigint class.. Assuming you have some member as value in bigint class, when you create a copy constructor, so you copy the member variable's value from passed instance to the new instance.

bigint::bigint(const bigint &that) {
        value = that.value; // copy value
}

if your instance member name is different, please change "value" to that in aboce code.