Adding BigInt's

[C++ Programming]

//WTF?
BigInt BigInt::add_bigint(BigInt add)
{
int carry = 0;
int temp;
bool carry2;
stack answer;
vector tempvector;
vector add_int = add.get_bigint();

while(bigint_int.size() > add_int.size())
add_int.insert(add_int.begin(), 1, 0);

while(bigint_int.size() < add_int.size())
bigint_int.insert(bigint_int.begin(), 1, 0);
cout