使用 STL sort(） func 用于我构建的类

我写了一个类，我希望它与STL算法sort（）函数一起使用。让我给出一些代码片段;

class bignum_index_cont
{
private:
mpz_class a;
long int index;
public:
bignum_index_cont() {a=0; index=0;}
bignum_index_cont(const bignum_index_cont &big) {a=big.a; index=big.index;}
void bignum_set(mpz_class &c, long int d) {a=c;index=d;}
bool operator==(bignum_index_cont &big) {return a==big.a;}
bool operator==(mpz_class &big) {return a==big;}
bool operator>(bignum_index_cont &big) { return a>big.a;}
bool operator>=(bignum_index_cont &big) {return a>=big.a;}
bool operator<(bignum_index_cont &big) {return a<big.a;}
bool operator<=(bignum_index_cont &big) {return a<=big.a;}
//some more functions..... that I think will not be needed here.
};

然后我在全球空间vector<bignum_index_cont> hashtx1(pow(2,20)+1);。现在，在main()我设法对vector<bignum_index_cont>的所有元素进行输入然后我决定对这个向量进行排序。所以，我打电话给，sort(hashtx1.begin(), hashtx1.end());..但我得到了大量的错误列表。它们是：

c:mingwbin..libgccmingw324.6.2includec++bitsstl_algo.h||In function '_RandomAccessIterator std::__unguarded_partition(_RandomAccessIterator, _RandomAccessIterator, const _Tp&) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<bignum_index_cont*, std::vector<bignum_index_cont> >, _Tp = bignum_index_cont]':|
c:mingwbin..libgccmingw324.6.2includec++bitsstl_algo.h:2253|70|instantiated from '_RandomAccessIterator std::__unguarded_partition_pivot(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<bignum_index_cont*, std::vector<bignum_index_cont> >]'|
c:mingwbin..libgccmingw324.6.2includec++bitsstl_algo.h:2284|54|instantiated from 'void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<bignum_index_cont*, std::vector<bignum_index_cont> >, _Size = int]'|
c:mingwbin..libgccmingw324.6.2includec++bitsstl_algo.h:5407|4|instantiated from 'void std::sort(_RAIter, _RAIter) [with _RAIter = __gnu_cxx::__normal_iterator<bignum_index_cont*, std::vector<bignum_index_cont> >]'|
C:UsersponeerDesktopCryptographybignum.cpp:121|40|instantiated from here|
c:mingwbin..libgccmingw324.6.2includec++bitsstl_algo.h|2212|error: no match for 'operator<' in '__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = bignum_index_cont*, _Container = std::vector<bignum_index_cont>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = bignum_index_cont&]() < __pivot'|
c:mingwbin..libgccmingw324.6.2includec++bitsstl_algo.h|2212|note: candidates are:|
C:UsersponeerDesktopCryptographybignum.cpp|39|note: bool bignum_index_cont::operator<(bignum_index_cont&)|
C:UsersponeerDesktopCryptographybignum.cpp|39|note:   no known conversion for argument 1 from 'const bignum_index_cont' to 'bignum_index_cont&'|
c:mingwbin..libgccmingw324.6.2includec++bitsstl_pair.h|207|note: template<class _T1, class _T2> bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)|
//+ a lot of errors similar to this
C:FilesGMPGMPincludegmpxx.h|3150|note: template<class T, class U> bool operator<(long double, const __gmp_expr<T, U>&)|
//+ a lot similar to this

请注意，如果我采用vector<mpz_class> hashtx1(pow(2,20)+1)并使用 sort（） 函数，它可以很好地编译。如何改进我的代码，使其与sort()函数配合使用？

另一点是，我甚至尝试使用递归 quicksort（） 函数对向量进行排序。但它在运行时终止。

void quicksort(long int left, long int right)
{
long int i=left, j=right;
bignum_index_cont pivot, temp;
pivot=hashtx1[(left+right)/2];
while(i<=j)
{
    while(hashtx1[i]<pivot)
        i++;
    while(hashtx1[j]>pivot)
        j--;
    if(i<=j)
    {
        temp=hashtx1[i];
        hashtx1[i]=hashtx1[j];
        hashtx1[j]=temp;
        i++; j--;
    }
}
quicksort(left, j);
quicksort(i, right);
}

我用quicksort(0,pow(2,20))来称呼它。