有人能告诉我这是否正确。我正试图重载我的<<我的动态数组类中的数组的运算符。
Specefically,
我可以在课程中加入std:ostream吗?这似乎并不严谨。编译器错误告诉我它应该只接受一个参数。
void print_array(std::ostream &os = cout)
{
for (int i = 0; i < size; i++) os << array[i] << endl;
}
std::ostream& operator<<(std::ostream& stream, dynamic_array const& data)
{
data.print_array(stream);
return stream;
}
动态数组类
/*
Needs a reszie function added
Merge sort is better for sequential, stable(equal elements not re-arranged, or
*/
#include "c_arclib.cpp"
template <class T> class dynamic_array
{
private:
T* array;
T* scratch;
void merge_recurse(int left, int right)
{
if(right == left + 1)
{
return;
}
else
{
int i = 0;
int length = right - left;
int midpoint_distance = length/2;
int l = left, r = left + midpoint_distance;
merge_recurse(left, left + midpoint_distance);
merge_recurse(left + midpoint_distance, right);
for(i = 0; i < length; i++)
{
if((l < (left + midpoint_distance)) && (r == right || array[l] > array[r]))
{
scratch[i] = array[l];
l++;
}
else
{
scratch[i] = array[r];
r++;
}
}
for(i = left; i < right; i++)
{
array[i] = scratch[i - left];
}
}
}
void quick_recurse(int left, int right)
{
int l = left, r = right, tmp;
int pivot = array[(left + right) / 2];
while (l <= r)
{
while (array[l] < pivot)l++;
while (array[r] > pivot)r--;
if (l <= r)
{
tmp = array[l];
array[l] = array[r];
array[r] = tmp;
l++;
r--;
}
}
if (left < r)quick_recurse(left, r);
if (l < right)quick_recurse(l, right);
}
public:
int size;
dynamic_array(int sizein)
{
size=sizein;
array = new T[size]();
}
void print_array(std::ostream &os = cout)
{
for (int i = 0; i < size; i++) os << array[i] << endl;
}
std::ostream& operator<<(std::ostream& stream, dynamic_array const& data)
{
data.print_array(stream);
return stream;
}
void print_array()
{
for (int i = 0; i < size; i++) cout << array[i] << endl;
}
int merge_sort()
{
scratch = new T[size]();
if(scratch != NULL)
{
merge_recurse(0, size);
return 1;
}
else
{
return 0;
}
}
void quick_sort()
{
quick_recurse(0,size);
}
void rand_to_array()
{
srand(time(NULL));
int* k;
for (k = array; k != array + size; ++k)
{
*k=rand();
}
}
void order_to_array()
{
int* k;
int i = 0;
for (k = array; k != array + size; ++k)
{
*k=i;
++i;
}
}
void rorder_to_array()
{
int* k;
int i = size;
for (k = array; k != array + size; ++k)
{
*k=i;
--i;
}
}
};
int main()
{
dynamic_array<int> d1(1000000);
d1.order_to_array();
clock_t time_start=clock();
d1.merge_sort();
clock_t time_end=clock();
double result = (double)(time_end - time_start) / CLOCKS_PER_SEC;
cout << result;
}
答案 0 :(得分:1)
将操作员放在班级之外:
template <class T> class dynamic_array
{
...
// if you need to use protected/private members:
friend std::ostream& operator<<(std::ostream& stream,
dynamic_array<T> const& data);
}
template <class T>
std::ostream& operator<<(std::ostream& stream, dynamic_array<T> const& data)
{
data.print_array(stream);
return stream;
}
答案 1 :(得分:1)
由于operator<<
的左操作数将是ostream而不是动态数组对象,因此需要将operator<<
实现为全局函数,而不是成员函数(成员函数重载始终是调用为object.operator<<(argument)
,因此其成员的对象必须为左操作数。
如果需要访问对象的内部,可以将其设为好友。如果(在这种情况下)它只使用对象的公共接口(在你的情况下是print_array),那么它可以只是一个普通的全局函数。
template <class T>
class dynamic_array {
// ...
};
template <class T>
std::ostream &operator<<(std::ostream &os, dynamic_array<T> const &a) {
a.print_array(os);
return os;
}
但就个人而言,我可能会让print_array
成为私人成员,并让全球operator<<
成为朋友。这减少了类的公共接口(即只有一种方法来打印dynamic_array而不是两个)而不会丢失功能(因为do 正好相同的东西)。